Aisha Fayomi1, M H Tahir2, Ali Algarni1, M Imran2, Farrukh Jamal2. 1. Faculty of Science, Department of Statistics, King Abdulaziz University, Jeddah, Saudi Arabia. 2. Department of Statistics, Faculty of Computing, The Islamia University of Bahawalpur, Bahawalpur 63100, Pakistan.
Abstract
The compounding approach is used to introduce a new family of distributions called exponentiated Bell G, analogy to exponentiated G Poisson. Several essential properties of the proposed family are obtained. The special model called exponentiated Bell exponential (EBellE) is presented along with properties. Furthermore, the risk theory related measures including value-at-risk and expected-shortfall are also computed for the special model. Group acceptance sampling plan is designed when a lifetime of a product or item follows an EBellE model taking median as a quality parameter. The parameters of the proposed model are estimated by considering maximum likelihood approach along with simulation analysis. The usefulness of the proposed model is illustrated by practical means which yield better fits as compared to several exponential related extended models.
The compounding approach is used to introduce a new family of distributions called exponentiated Bell G, analogy to exponentiated G Poisson. Several essential properties of the proposed family are obtained. The special model called exponentiated Bell exponential (EBellE) is presented along with properties. Furthermore, the risk theory related measures including value-at-risk and expected-shortfall are also computed for the special model. Group acceptance sampling plan is designed when a lifetime of a product or item follows an EBellE model taking median as a quality parameter. The parameters of the proposed model are estimated by considering maximum likelihood approach along with simulation analysis. The usefulness of the proposed model is illustrated by practical means which yield better fits as compared to several exponential related extended models.
Effective implementation of mathematical and statistical models enables the actuarial scientists to know as much as possible about future claims in a portfolio. These models serve as a guide to achieve better business and risk management decision and policies. Actuaries usually deal with a complex data such as right skewed, unimodal, and having heavy tail. The readers are referred to works of Klugman et al. [1], Cooray and Ananda et al. [2], Lane [3], Vernic [4], and Ibragimov et al. [5]. At the same time, they are eager on some flexible models which are capable of capturing the behaviours of such data to finding along with information when the real development deviates from the expected. The classical models are limited with their tail properties and goodness of fit tests. For instance, Pareto, Lomax, Fisk, and Dagum distribution are excessively used to model statistical size distributions in economics and actuarial sciences but often failed to provide better fits for many application. The Weibull distribution is appropriate for small losses but fail to uncover adequate trend, level, and trajectory for large losses [6]. The reader are referred to [7] for detail discussion on statistical size distributions which can be used in economics and actuarial sciences. To overcome the drawback of classical models, a substantial progress on persistent base related to distribution theory is documented in statistical literature. From the last couple of decades, the emerging trend has been seen in the generalization of the existing classical models. The models are extended by adopting different modes of adding one or more additional shape parameter(s) in the distribution. The basic aim of this whole exercise is to improve the tail properties as well as goodness of fit test of the classical models. There are several well-known generators which are documented in the statistical literature; the readers are referred to the works of Tahir and Nadarajah [8], Tahir and Cordeiro [9], Maurya and Nadarajah [10], and Lee et al. [11].Several new models related to claim data have recently been reported in statistical literature. Ahmad et al. [12] proposed a new method to define heavy-tailed distributions called the exponentiated power Weibull distribution with application to medical care insurance and vehicle insurance. Calderin–Ojeda and Kwok [13] presented a new class of composite model by using the Stoppa distribution and mode matching procedure and modelling the actuarial claims data of mixed sizes. Ahmad et al. [14] suggested nine new methods to define new distributions suitable for modelling heavy right-tail data with application to medical care insurance and vehicle insurance. Afify et al. [15] proposed a new heavy-tailed exponential distribution with application to unemployment claim data. Ahmad et al. [16] introduced a class of claim distributions useful in a number of lifetime analyses. A special submodel of the proposed family, called the Weibull claim model, is considered in detail with claim data application. Among classical discrete distributions, Poisson distribution is a most frequently used distribution for count data. Furthermore, it is extended into G-class and several transformation and family of distributions have been proposed. A detail review study on Poisson generated family of distributions, extensions, and transformation is recently presented by [10]. Castellares et al. [17] introduced a discrete Bell distribution from well-known Bell numbers, as a competitor or counterpart to Poisson distribution which exhibits many interesting properties such as a single parameter distribution, and it belongs to one-parameter exponential family of distributions and the Poisson distributions. They investigated that the Poisson model cannot be nested into the Bell model, but small values of the parameter the Bell model tends to Poisson distribution. Furthermore, the Bell model is infinity divisible and has larger variance as compared to the mean, which can be used to overcome the phenomenon of over-dispersion and zero-vertex for count data. The characteristics of the Bell model motivated us to develop a generalized class of distributions through compounding and to compare its mathematical and empirical characteristics with compounded Poisson-G class and its special models.The rest of the study is organized as follows. In Section 2, we define the proposed EBell-G family of distributions. Section 3 provides the general mathematical and structural properties of EBell-G family of distributions including linear representation of density, quantile function, rth moments, probability weighted moments, analytical shapes of the density and hazard rate, entropy measures, reversed order statistics, upper record statistics, stochastic ordering, and parameters' estimation by using maximum likelihood estimation. Section 4 illustrates the layout of the special model called EBellE as well as its essential properties, while Section 5 shows the commonly used actuarial measures, specially value-at-risk and expected-shortfall. Section 6 are illustrated group acceptance sampling plane when a lifetime of a certain product or item follows the EBellE model which is presented. The simulation analysis is presented in Section 7, and Section 8 contains the application of real datasets. The concluding remarks are given in Section 9.
2. Layout and Formulation of EBell-G Family
A single parameter discrete Bell distribution has been recently introduced by Castellares et al. [17], which is an analogy to discrete Poisson distribution but provides better fits compared to other discrete models including the Poisson model. The following expression given by Bell [18] iswhere B denote the Bell numbers and can be derived from the following mathematical expression:
Remark 1 .
The Bell number B in (2) is the nth moment of the Poisson distribution with parameter equal to 1.By considering equations (1) and (2), Castellares et al. [17] introduced a single-parameter Bell distribution defined by the following probability mass function (pmf) as
Proposition 1 .
LetXfollow a discrete Bell model with parameterλ; then, the following expression represents the pmf of Bell truncated model asWe first give the motivation for the proposed family. Suppose a system is having N subsystems that are working or functioning independently at a given specific time. Here, Y denotes the life of ith subsystem and θ parallel units constitutes the subsystem. Furthermore, the system will fail or remain functioning if all the subsystem fail; this is for the parallel system. On the contrary, for series system, the failure of any subsystem yields complete destruction of the whole system. Let us have a random variable (rv)N that follows any discrete distribution having pmf ℙ(N=n). Here, we suppose that a component Z,……Z having failure time for the ith subsystem are i.i.d. with suitable cdf depending upon the vector τ, say for X > 0, T[G(x, τ), θ]=G(x, τ). If we define Y=min{Y1,……Y}, then the conditional cdf of Y given N is as follows:The unconditional cdf of Y corresponding to (5) is given byBy using the Bell truncated model given in Eq. (4) and then using Eq. (6), the unconditional cdf of X is defined below as follows.
Proposition 2 .
LetX∼EBell-G(λ, θ, ξ), forx > 0andλ, θ, ξ > 0; then, its cumulative distribution function (cdf) having baseline pdf and cdf respectivelyg(x)andG(x)is given by
Proposition 3 .
LetX∼EBell-G(λ, θ, ξ)forx > 0andλ, θ, ξ > 0; then, its probability distribution function (pdf) having Eq. (8), with baseline pdf and cdf respectivelyg(x)andG(x), is given by
Proposition 4 .
LetX∼EBell-G(λ, θ, ξ)forx > 0andλ, θ, ξ > 0; then, its survival function (sf) and hazard rate function (hrf) are, respectively, given by
3. Properties of the EBell-G Family
This section provides some mathematical properties of the EBell-G family of distributions.
3.1. Quantile Function
Quantile function (qf) is an important measure for generating random numbers and several other important uses in quality control sampling plans and in risk theory; the two important commonly used measures value-at-risk (VaR) and expected-shortfall (ES) which depend on qf and is given as follows.
Proposition 5 .
LetX∼EBell-G(λ, θ, ξ)forx > 0andλ, θ, ξ > 0; then, the expression of qf is given below, whereu ~ uniform(0,1), and by replacingu=0.5, it yields the median of the EBell-G:
3.2. Analytic Shapes of the Density and Hazard Rate Function
The analytical shapes of the density and hrf can be yielded for EBellE, respectively, as follows:
3.3. Useful Expansions
Here, we show the useful expansion for EBell-G density can be used to drive several important properties by taking into account the following two series to obtain the expansion for EBell-G.
Proposition 6 .
The generalized binomial expansion which holds for any real noninteger b and |t| < 1isThe power series for exponential function is given by Bourguignon et al. [19] and is given as follows:Therefore, by using Eq. (11) to Eq. (8), we can deduce pdf and cdf, simultaneously, aswhereare constants satisfying ∑w=1. Eq. (12) represents exp-G, that is, h(x) and the term θ(v+1) is treated as the power parameter. By using Eq. (12), numerous properties of G-class can be obtained.
3.4. Mathematical Properties
One can derive some important mathematical properties by considering Eq. (12). The rth raw moment of X is given bywhere E[X] follows a exp-G with θ(v+1) treated as the power parameter, and by taking r=1, in (14), yields the mean for X.The incomplete moments are important and have many practical uses. The expression of sth incomplete moments, denoted by φ(t), is defined by φ(t)=∫−xf(x)dx and can be obtained by using Eq. (12) asThe first incomplete moment of the EBell-G family can be obtained as by taking s=1 in Eq. (15). The sth incomplete moment is an important to compute several measures, namely, mean deviations from mean and median, mean waiting time, conditional moments, and income inequality measures among others.
3.5. Probability Weighted Moments
The (s, r)th probability weighted moments (PWM) of X following the EBell-G family, say ρ, is formally defined byBy using Eq. (7) and Eq. (8), we can obtainwhere
3.6. Entropy Measures
The entropy measures are important to underline the randomness or uncertainty or diversity of the system. The most frequently used index of dispersion in ecology as well as in statistics is called the Rényi entropy I(x) and is defined by the following expression:where δ > 0 and δ ≠ 1, which then followswhereThe Shannon entropy say, H(x), can be obtained by the following expression:where q > 0 and q ≠ 1 and
3.7. Order Statistics
Here, we derived the explicit expression for the ith-order statistics for EBell-G, say f(x). Let a sample of size be n; then, the pdf of ith-order statistics is defined byBy using Eq. (7) and Eq. (8), the density for EBell-G can be written aswhereThe sth moment of order statistic can be obtained aswhere μ( is the sth moment of Exp-G distribution with power parameter θ(j+1).
3.8. Reversed Order Statistics
The reversed order statistics can be used when x1,……, x are arranged in the decreasing order; for more detail, see the work of Jamal et al. [20]. The pdf of X, represented by f(x)=f(x), is defined byandConsiderBy using Eq. (10), we can obtainThen, by using Eq. (11), we can haveLet us considerAfter simplification, we have shapes:Finally,The reduced form will bewhere h=θ(j+1)g(x)G(x) andThe pth moment of reversed-order statistic can be obtained aswhere μ( is the pth moment of Exp-G distribution with power parameter θ(j+1).
3.9. Upper Record Statistics
Record value is an important measure in many practical areas, for instance, economics data and weather and athletic events. Let us consider (X) a sequence of independent rvs having the same distribution. Let us denote by F(x) and f(x) the related cdf and pdf of EBellE distribution, respectively, and X be the ith-order statistic as described previously. For fixed k ≥ 1, the pdf of kth upper record statistic is defined bywhere R(x)=−ln[1 − F(x)] correspond to the cumulative hazard rate function related to F(x). Eq. (20) can also be expressed for R(x)=e[1 − e−], by using (7), asConsidering the last terms,and after using series, we obtainUsing power series given in Eq. (11), we obtainNow, the above expression becomesBy using Eq. (11) again, we obtainFinally, we haveThe reduced form becomeswhere h(x)=θ(q+1)g(x)G(x) andA random sample of 50 is generated from the EBellE model using Eq. (23), and then, take k=3 and α=β=λ=0.5. Table 1 shows a random sample of 50 from the EBellE model along with upper X and lower X records values. The plot of lower and upper record values is illustrated in Figure 1. The Records package is used in R-Statistical Computing Environment to compute X and X records' values.
Table 1
Upper and lower record values from EBellE generated data.
n=50; k=3; α=θ=λ=0.5
XU(n)
XL(n)
0.291681
0.608776
1.872313
0.338539
0.064955
0.083234
0.291681
0.083234
0.399718
0.508271
0.00626
0.042802
0.185290
0.18529
0.18529
0.009471
1.132511
0.022277
0.000141
0.291681
0.083234
0.747575
0.461116
0.118013
2.358966
0.894275
0.509482
0.064443
0.005202
0.120005
0.163145
0.180631
0.052073
0.608776
0.063257
0.041376
0.187393
0.799698
0.983506
0.019917
0.747575
0.041376
0.064443
0.001881
1.599134
1.463232
0.000197
1.132511
0.009471
0.063257
0.059046
0.047385
3.757872
0.259716
1.579419
0.00626
0.509482
0.156173
1.107195
0.719695
0.007713
1.599134
0.005202
0.188353
1.579419
0.118276
0.280922
1.303078
1.872313
0.001881
Figure 1
Plot of upper (a) and lower (b) record values of the EBellE model at some parametric values.
3.10. Stochastic Ordering
Stochastic ordering is another important tool in statistics to define the comparative behaviour specifically in reliability theory. Suppose the two rvs, say X1 and X2 and under specific circumstance; let us consider that rv X1 is lower than X2; the readers can refer to the work of Khan et al. [21] for detailed illustration on four stochastic ordering and their well-established relationships.
Theorem 1 .
LetX
1∼EBell-G(λ1, θ; ξ)andX2∼EBell-G(λ2, θ; ξ). Ifα1 ≤ α2, thenX1≤X2:Proof. First, we have the ratioNow, considerAfter simplification, we obtainIf λ1 < λ2, we obtainThus, f1(x)/f2(x) is decreasing in x, and hence, X1≤X2. This completes the proof.
3.11. Estimation of Family Parameters
This section is about estimation of the unknown parameters estimation of the EBell-G model by taking into account the popular estimation method known as maximum likelihood estimation (MLE). There are several advantages of MLE over other estimation methods; for instance, the maximum likelihood estimates fulfil the required properties that can be used in constructing confidence intervals as well as maximum likelihood estimates delivering simple approximation very handy while working the finite sample. ℓ(.) represent the vector parameters ϕ=(λ, θ, ξ)⊤; then,where g=∂/∂ξg(x; ξ) and G=∂/∂ξG(x; ξ) are derivatives of column vectors of the same dimension of ξ, and by setting ϕ=0, ϕ=0, and ϕ=0, the MLEs can be yielded by solving the above equations simultaneously.
Proposition 7 .
A randomly selected sample of sizenis under EBell-G; then, the score vector(ϕ, ϕ, ϕ)is given by
4. Layout of the EBellE Model
Due to the closed form solution of many real problems and simplicity, exponential distribution is commonly employed in lifetime testing as well as reliability analysis. However, the exponential distribution failed to yield better fits when hazard rates are nonconstant. However, several studies showed that extended exponential distribution or when it is used as baseline model provides better fits [22-24]. In the present study, we used exponential distribution as a baseline model which yielded flexibility in both pdf and hrf shapes given in Figures 2 and 3, respectively. We now define the EBellE distribution by taking the exponential model as baseline, with the following expression of densities g(x)=α exp(−αx) and G(x)=1 − exp(−αx) for x > 0 and α > 0, by setting these densities in (7) and (8) yielded the following expression for the proposed EBellE distribution. Then, the cdf and pdf are of the EBellE distribution, respectively.
Figure 2
Plots of EBellE density for some parametric values.
Figure 3
Plots of hazard rate of EBellE for some parametric values.
Proposition 8 .
LetX∼EBellE(λ, θ, α), forx > 0andλ, θ, α > 0; then, its cdf is given by in Eq. (7):
Proposition 9 .
LetX∼EBellE(λ, θ, α), forx > 0andλ, θ, α > 0; then, its pdf is given by in Eq. (8):The exponential distribution quantile function becomes Q(u)=Q(z)=[−1/αlog(1 − z)]; using (9), z={1 − λ−1[log{log{1 − u{1 − exp[1 − e]}}+exp(λ)}]}. The quantile function of x can be expressed asThe sf and the hrf of the EBellE model can be obtained as
4.1. Properties of the EBellE Model
First, we will deduce linear representation of EBellE density to obtain useful properties of that model. By using Eq. (12),After applying Eq. (10), it reduces towhere π[x; α(p+1)] is a exp-exponential density with α(p+1) parameter andIt is obvious from Eq. (25) that the EBellE density is a linear combination of exponential densities, and therefore, one can obtain several properties using Eq. (25).
4.1.1. The Expression of rth Moment
Proposition 10 .
LetX∼EBellE(λ, θ, α), forx > 0andλ, θ, α > 0; then, itsrth moment can be written as by taking into account Eq. (25):By setting r = 1 yielded the mean of the EBellE model.
4.1.2. The Expression of sth Incomplete Moment
Proposition 11 .
LetX∼EBellE(λ, θ, α), forx > 0andλ, θ, α > 0; then, itssth incomplete moment can be written as by taking into account Eq. (25):By setting s = 1 yielded the first incomplete moment of the EBellE model. Table 2 shows the first four raw moments, central moments, coefficient of variation, coefficient of kurtosis, and Pearson's coefficient of skewness for some parametric values. Six different scenarios of parametric values are used in order to compute different measures of dispersion. S-1 = [α=2.5, θ=1.0, λ=0.2], S-2 = [α=1.5, θ=1.4, λ=1.2], S-3 = [α=0.85, θ=0.75, λ=1.2], S-4 = [α=0.85, θ=2.5, λ=0.2], S-5 = [α=4.85, θ=0.22, λ=0.12], and S − 6=[α=2.5, θ=3.85, λ=1]. The following relationship is used to obtain the central moments: μ2=μ2′ − (μ1′)2, μ3=μ3′ − 3μ1′μ2′+2(μ1′)3, and μ4=μ4′ − 4μ3′μ1′+6μ2′(μ1′)2 − 3(μ1′)4. The moment-based measure of skewness and kurtosis is obtained by using β1=μ32/μ23 and β2=μ4/μ22, respectively. Pearson's coefficient of skewness is simply square root of β1, and coefficient of kurtosis is computed as β2 − 3. Furthermore, we present the mean, variance, skewness, and kurtosis of EBellE in Figures 4 and 5, respectively, utilizing these results. Some plots of Bonferroni and Lorenz curve are also depicted in Figure 6.
Table 2
Measures of dispersion of the EBellE model for some parametric value.
Measures
S-1
S-2
S-3
S-4
S-5
S-6
μ1′
0.3591
0.3401
0.3061
1.8307
0.0586
0.4655
μ2′
0.2722
0.2740
0.4064
5.0198
0.0191
0.3953
μ3′
0.3181
0.4159
1.1396
18.8237
0.0109
0.4156
μ4′
0.5022
0.9724
4.8754
90.8662
0.0087
0.5970
μ2
0.1432
0.1583
0.3127
1.6682
0.0157
0.1786
μ3
0.1174
0.2150
0.8237
3.5258
0.0079
0.0654
μ4
0.2061
0.5567
3.6822
20.2673
0.0065
0.1962
β1
4.6922
11.6396
22.1826
2.6779
16.2771
0.7506
β2
10.046
22.2016
37.6498
7.2831
26.3259
6.1551
CS
2.1662
3.4117
4.70980
1.6364
4.0345
0.8663
CK
7.0463
19.2016
34.6498
4.2831
23.3259
3.1551
Figure 4
Graphical illustration of mean (a) and variance (b) of the EBellE model.
Figure 5
Graphical illustration of skewness (a) and kurtosis (b) of the EBellE model.
Figure 6
Plot of f Bonferroni (a) and Lorenz (b) curves of EBellE for some parametric values.
4.1.3. The Expression of r th Conditional Moment
From actuarial prospective, conditional moments are important; let EBellE be (λ, θ, α) for x > 0 and λ, θ, α > 0; then, its r th conditional moment can be written by using Equation (64):
4.1.4. Two Expression of MGF
Let X ∼ EBellE (λ, θ, α) for x > 0 and λ, θ, α > 0; then, its moment generating function by using Wright generalization hypergeometric function is given asConsider I=∫0exp(tx)exp[−a(p+1)x]dx and exp(tx)=∑t/m!x; equation (70) is reduced toBy using (70), Equation (71) yielded asThe other representation of mgf is given by
4.1.5. Order Statistics
The sth moment of order statistic can be obtained by using (41):Simplification yielded the expression of sth moments of order statistics:where .To study the distributional behaviour of the set of observation, we can use minimum and maximum (min-max) plot of the order statistics. Min-max plot depends on extreme order statistics, and it is introduced to capture all information not only about the tails of the distribution but also about the whole distribution of the data. Figure 7 shows the min and the max order statistics for some parametric values and depends on E(X1:) and E(X), respectively.
Figure 7
Min-Max plot of order statistics of the EBellE model for some parametric values.
4.1.6. Stochastic Ordering
Let X and Y be the two rvs from EBellE distribution with the assumption previously illustrated in Section 3 given that λ1 < λ2, and for X1≤X2, f1(x)/f2(x) shall be decreasing in x if and the only if the following results holds:
4.1.7. Rényi Entropy
The Rényi entropy for the EBellE model by using Eq. (22) given under and δ > 0 and δ ≠ 1:where , and the graphical demonstration of Rényi entropy of EBellE at varying of the parameters is given in Figure 8.
Figure 8
Plot of Rényi entropy of the EBellE model for some parametric values.
4.1.8. Reliability
Reliability is an important measure, and several applications are documented in the field of economics, physical science, and engineering. Reliability enables us to determine the failure probability at certain point in a time. Let X1 and X2 be the two random variable following the EBellE distribution. The component fails if the applied stress exceeds its strength; if X1 > X2, the component will perform satisfactory. Reliability is defined by the following expression. Here, we derive the reliability of the EBellE model when X1 and X2 have independent f1(x; λ1, θ, α) and F2(x; λ2, θ, α) with identical scale (α) and shape (θ) parameters. The reliability is given byBy using equations (14) and (15), we get the pdf and the cdf of EBellE, respectively, as follows:Hence,Therefore,By using gamma function, the above expression is reduced towhere .
4.2. Estimation
The log-likelihood function for the vector of parameters ϕ=(λ, θ, α)⊤ for model given in (60) is given byThe components of the score vector U(ϕ) areBy setting U=0, U=0 and U=0, the MLEs can be yielded by solving the above equations simultaneously.
5. Actuarial Measures
5.1. Value at Risk
Value-at-risk or quantile risk or simply VaR is the extensively used as a standard finial market risk measure. It plays an important role in many business decisions; the uncertainty regarding foreign market, commodity price, and government policies can affect significantly firm earnings. The loss portfolio value is specified by the certain degree of confidence say q(90%, 95%or99%). VaR of random variable X is simply the qth quantile of its cdf. If X follows the EBellE model; then, its VaR is defined by the following expression:
5.2. Expected Shortfall
The other important financial risk measure is called an expected-shortfall (ES) introduced in [25] and generally considered a better measure than value-at-risk. It is defined by the following expression:For 0 < q < 1, using Eq. (85) in Eq. (86), yielded ES for EBellE. In Figure 9, the graphical representation of VaR and ES measures for some parameter combinations is presented.
Figure 9
Plot of VaR (a) and ES (b) of EBellE distribution for some parametric values.
5.3. Tail Value at Risk
The problem of risk measurement is one of the most important problems in the risk management. From finance and insurance prospective, Tail value-at-risk (TVaR) or tail conditional expectation or conditional tail expectation is an important measure and define as the expected value of the loss, given the loss is greater than the VaR:By using (25) in (35) yielded tail value-at-risk as
5.4. Tail Variance
Tail variance (TV) has yet another important risk measure because it considers the variability of the risk along the tail of distribution; it is defined as from the following expression:Consider I=E[X2|X > x]:Using (88) and (90) in (89), we obtain the expression for tail variance for the EBellW model.
5.5. Tail Variance Premium
The TVP is the mixture of both central tendency as well as dispersion statistics. It is defined by the following:where 0 < δ < 1. Using expressions (89) and (88) in (91), we obtain the tail variance premium for the EBellW model.
5.5.1. Numerical Illustration of VaR and ES
Here, we demonstrate the numerical as well as graphical presentation of the two important risk measures ES and VaR. The comparative study of ES and VaR of the proposed EBellE model with their counterpart exponentiated exponential Poisson (EEP) and exponentiated exponential (EE) model is performed by taking MLEs' estimates of the parameters for the models in all datasets. It is worth emphasising that a model with higher values of the risk measures is said to have a heavier tail. Table 3 provides the numerical illustration of the ES and VaR for EBellE and EEP and EE model of all three datasets and yielded that the EBellE model has higher values of both the risk measures as compared to their counterpart EEP and EE model. The graphical demonstration of the models from Figures 10–12 also revealed that the proposed model has slightly heavier tail than EEP and EE model. The reader should refer to Chan et al. [26] for detail discussion of VaR and ES and their computation by using an R-Programming Language. A sample of 100 is randomly drawn, and the effect of shape and scale parameters of the proposed models is underlined for both risk measures. Various combinations of the scale and shape parameters are executed I = [α=2.1, θ=1.1, λ=0.22], II = [α=1.4, θ=0.5, λ=1.2], III = [α=0.6, θ=0.5, λ=0.5], and IV = [α=0.4, θ=2, λ=2.5] and change in the curve of VaR and ES are illustrated in Figure 4.
Table 3
The detailed summary of ES and VaR of the datasets.
q
Data 1
Data 2
Data 3
EBellE
EEP
EE
EBellE
EEP
EE
EBellE
EEP
EE
ES
0.50
53.614
52.009
50.251
131.699
97.948
132.350
3.7219
3.3382
2.7068
0.60
54.991
53.384
51.710
133.963
99.956
134.106
4.1545
3.7429
3.0869
0.65
56.385
54.776
53.193
136.192
101.971
135.884
4.6243
4.1816
3.4998
0.70
57.816
56.204
54.716
138.409
104.019
137.706
5.1411
4.6628
3.9517
0.75
59.308
57.691
56.301
140.640
106.130
139.596
5.7192
5.1982
4.4508
0.80
60.895
59.268
57.977
142.919
108.345
141.589
6.3803
5.8056
5.0098
0.85
62.629
60.984
59.786
145.287
110.725
143.734
7.1616
6.5147
5.6484
0.90
64.608
62.927
61.801
147.816
113.379
146.116
8.1359
7.3824
6.4018
0.95
67.058
65.299
64.182
150.656
116.561
148.922
9.4909
8.5496
7.3485
0.99
69.963
68.033
66.726
153.517
120.178
151.909
11.4198
10.1086
8.4328
VaR
0.50
68.734
67.108
66.235
156.895
120.079
151.618
8.3035
7.6248
6.7247
0.60
71.581
69.955
69.327
160.872
124.043
155.273
9.5524
8.7894
7.8348
0.65
74.699
73.063
72.686
165.034
128.320
159.234
11.0126
10.1406
9.1054
0.70
78.208
76.545
76.416
169.485
133.053
163.622
12.7655
11.7457
10.5851
0.75
82.297
80.575
80.673
174.376
138.458
168.619
14.9445
13.7133
12.3490
0.80
87.289
85.450
85.714
179.950
144.904
174.526
17.7899
16.2351
14.5235
0.85
93.819
91.748
92.016
186.649
153.099
181.896
21.7938
19.6942
17.3454
0.90
103.403
100.823
100.649
195.463
164.722
191.974
28.1974
25.0281
21.3472
0.95
121.320
117.303
115.012
209.589
185.624
199.436
41.6908
35.6465
28.2275
0.99
171.119
161.023
147.586
249.567
243.769
235.646
89.1873
69.5513
44.2822
Figure 10
Plot of ES (a) and VaR (b) of EBellE distribution Data-1.
Figure 11
Plot of ES (a) and VaR (b) of EBellE distribution Data-2.
Figure 12
Plot of ES (a) and VaR (b) of EBellE distribution Data-3.
6. Designing of GASP under the EBellE Model
Saving time and cost is attributed to the sampling method. Certain quality control checks are implemented either accepting or rejecting a lot under various sampling plans. This section based on the illustration of GASP under the assumption when the lifetime distribution of an item followed a EBellE model with known parameter λ and θ having cdf in Eq. (96). In a GASP, let a random sample of size n be taken and distributed in such a way; that is, n=r × g and r items for each group are kept on life testing under predefined time. If the number of failures in each group are higher than the acceptance number c, the performed experiment is truncated. The reader is referred to the work of Aslam et al. [27] and Khan and Alqarni [28] for simple illustration of GASP and application to real data. Designing the GASP reduced both the time and cost. Several lifetime traditional and extended models are used [27, 29–32] in designing the GASP by taking into account the quality parameter as mean or median; usually, for skewed distribution, median is preferable [27].The GASP is simply the extension of ordinary sampling plan (OSP), i.e., the GASP tends to OSP by replacing r=1, and thus, n=g [33].GASP is based on the following form; first of all, select g and allocate predefine r items to each group so that the sample of size of the lot will be n=r × g. Secondly, select c and t0 representing the acceptance number and the experiment time, respectively. Thirdly, do experiment simultaneously for g groups and record the number of failure for each group. Finally, conclusion is drawn either accepting or rejecting the lot; the lot is accepted if there is no more than c failure occurring in each and every group; otherwise, reject a lot. The accepting probability of a lot yielded by the following expression:where the probability that an item in a group fail before t0 is denoted by p and yielded by inserting (61) in (96). Let the lifetime of an item or product follow a EBellE with known parameters θ and λ, with cdf given for t > 0:qf of the EBellE model using (61) is given by, and if p=0.5 yielded median lifetime distribution for a product or item,By taking η as follows,Eq. (94) becomes by replacing η; henceforth, α=−η/m and t=m0a1, m=−1/αη. The ratio of a of product mean lifetime ti and the specified life time m/m0 can be used to express the quality level of product. By replacing α=−η/m and t=m0a1 in Eq. (96) yielded the probability of failure given byFrom Eq. (96), for chosen θ and λ, p can be determined when a1 and r2 are specified, where r2=m/m0. Here, we define the two failure probabilities say p1 and p2 corresponding to the consumer risk and producer risk, respectively. For a given specific values of the parameters θ and λ, r2, a1, β, and γ, we need to evaluate the value of c and g that satisfy the following two equation simultaneously:where the mean ratio at consumer's risk and at producer's risk, respectively, is denoted by r1 and r2 and the probability of failure to be used in the above expression is as follows:From Tables 4 and 5, with β=0.25, a1 = 0.5, and r2 = 4 and taking r = 5, there are 40 groups or 200 (40 × 5=200); total units are needed for lifetime testing. While on the contrary, significant reduction can be observed in groups or number of units to be tested under the identical circumstances when r = 10; a total of 3 groups or 30 (3 × 10=30) item are needed for life testing. Here, we prefer the group size 10. Similarly, when β = 0.25, a1 = 1, and r2 = 4 and taking r = 5, there are 7 groups or 35 (7 × 5=35); total units are needed for life testing. While, on the contrary, in the number of units to be tested under the identical circumstances when r = 10, a total of 2 groups or 20 (2 × 10=20), items are needed for life testing. Here, we prefer the group size 10.
Table 4
GASP under the EBellE model, θ=1 and λ=1.25, showing minimum g and c.
β
r2
r=5
r=10
a1=0.5
a1=1
a1=0.5
a1=1
g
c
p(a)
g
c
p(a)
g
c
p(a)
g
c
p(a)
0.25
2
–
–
–
–
–
–
–
–
–
–
–
–
4
40
3
0.9860
7
3
0.9721
3
3
0.9701
2
4
0.9624
6
8
2
0.9815
3
2
0.9559
2
2
0.9565
1
3
0.9748
8
8
2
0.9917
3
2
0.979
2
2
0.9792
1
3
0.9899
0.1
2
–
–
–
–
–
–
–
–
–
–
–
–
4
66
3
0.9770
12
3
0.9527
5
3
0.9507
5
5
0.9843
6
12
2
0.9724
12
3
0.9881
5
3
0.9875
2
3
0.9503
8
12
2
0.9875
4
2
0.9721
3
2
0.9689
2
3
0.9800
0.05
2
–
–
–
–
–
–
–
–
–
–
–
–
4
85
3
0.9705
95
4
0.9845
17
4
0.9798
7
5
0.9781
6
16
2
0.9633
15
3
0.9852
7
3
0.9825
2
3
0.9503
8
16
2
0.9834
5
2
0.9652
3
2
0.9689
2
3
0.9800
0.01
2
–
–
–
–
–
–
–
–
–
–
–
–
4
131
3
0.9549
146
4
0.9763
26
4
0.9693
10
5
0.9688
6
131
3
0.9899
23
3
0.9774
10
3
0.9751
5
4
0.9803
8
24
2
0.9752
7
2
0.9517
10
3
0.9910
3
3
0.9701
Remark: a large sample size in required cells contains hyphens (–).
Table 5
GASP under the EBellE model, θ=1 and λ=1.50, showing minimum g and c.
β
r2
r=5
r=10
a1=0.5
a1=1
a1=0.5
a1=1
g
c
p(a)
g
c
p(a)
g
c
p(a)
g
c
p(a)
0.25
2
–
–
–
–
–
–
–
–
–
–
–
–
4
41
3
0.9866
7
3
0.9735
3
3
0.9718
2
4
0.9644
6
8
2
0.9824
3
2
0.9578
2
2
0.9584
1
3
0.9761
8
8
2
0.9921
3
2
0.98
2
2
0.9802
1
3
0.9905
0.1
2
–
–
–
–
–
–
–
–
–
–
–
–
4
68
3
0.9779
12
3
0.955
5
3
0.9535
5
5
0.9854
6
13
2
0.9715
12
3
0.9888
5
3
0.9883
2
3
0.9528
8
13
2
0.9872
4
2
0.9734
3
2
0.9705
2
3
0.9811
0.05
2
–
–
–
–
–
–
–
–
–
–
–
–
4
88
3
0.9715
95
4
0.9855
17
4
0.9814
7
5
0.9796
6
16
2
0.9651
15
3
0.9861
7
3
0.9836
2
3
0.9528
8
16
2
0.9843
5
2
0.9669
3
2
0.9705
2
3
0.9811
0.01
2
–
–
–
–
–
–
–
–
–
–
–
–
4
135
3
0.9565
146
4
0.9778
26
4
0.9716
10
5
0.9709
6
135
3
0.9903
23
3
0.9787
10
3
0.9767
5
4
0.9816
8
25
2
0.9755
7
2
0.954
5
2
0.9513
3
3
0.9718
Remark: a large sample size in required cells contains hyphens (–).
7. Simulation Analysis
Simulation analysis is very important tools in statistics and used to determine the performance of estimates over predefine replication at varying sample sizes. So, this section is primarily based on simulation analysis in order to underline the performance parameter estimates of the proposed EBellE model. A simulation process is replicated 1000 times with at varying sample sizes, n = 25, 50, 100, and 500. In Table 6, various combinations of the parameter α, θ, and λ are considered, say scenario I = [α=1.5, θ=0.3, λ=0.5], scenario II = [α=0.15, θ=0.5, λ=0.5], and scenario III = [α=1, θ=0.2, λ=0.17]. The finding of the simulation analysis yielded that bias, mean square error (MSE), and average width (AW) of the confidence interval of the parameters reduced as sample size increases. On the contrary, the coverage probabilities (CPs) touch 95% nominal level. So, therefore, the MLEs and their asymptotic results can be used for estimating and constructing confidence intervals for proposed EBellE model parameters. Readers are referred to the work of Sigal et al. [34] for simple but comprehensive way in designing Monte Carlo simulation study by using R-programming language:
Table 6
Biases, MSEs, CPs, and AWs for different scenarios.
Scenario I
Scenario II
Scenario III
n
α
θ
λ
n
α
θ
λ
n
α
θ
λ
Biases
25
0.282
0.050
0.152
25
0.006
0.063
0.176
25
0.162
0.067
0.375
50
0.098
0.028
0.105
50
0.002
0.038
0.112
50
0.038
0.048
0.289
100
0.046
0.015
0.050
100
0.010
0.017
0.042
100
−0.007
0.031
0.196
500
0.028
0.005
0.009
500
0.001
0.000
-0.009
500
0.008
0.007
0.043
MSE
25
1.398
0.010
0.162
25
0.007
0.023
0.198
25
0.669
0.009
0.258
50
0.584
0.005
0.122
50
0.004
0.012
0.145
50
0.204
0.005
0.169
100
0.262
0.002
0.073
100
0.001
0.006
0.094
100
0.001
0.006
0.094
500
0.055
0.001
0.021
500
0.000
0.001
0.029
500
0.000
0.001
0.029
CPs
25
0.968
0.955
0.982
25
0.972
0.963
0.959
25
0.957
0.938
0.930
50
0.965
0.960
0.980
50
0.976
0.957
0.971
50
0.925
0.927
0.904
100
0.955
0.953
0.969
100
0.940
0.954
0.972
100
0.928
0.927
0.903
500
0.930
0.945
0.950
500
0.940
0.948
0.964
500
0.881
0.965
0.945
AWs
25
5.001
0.396
2.461
25
0.405
0.627
2.721
25
3.158
0.316
2.375
50
3.123
0.276
1.782
50
0.279
0.455
2.047
50
1.873
0.222
1.751
100
2.078
0.196
1.276
100
0.082
0.327
1.485
100
1.170
0.154
1.271
500
0.887
0.088
0.573
500
0.082
0.149
0.671
500
0.443
0.067
0.607
8. Practical Implementation of the Proposed EBellE Model
8.1. Actuarial Data
Here, we demonstrate the flexibility and usefulness of the proposed EBellE model by practical means. Three insurance claim datasets are used; the first two datasets based on unemployment claims from July 2008 to April 2013, reported by the Department of Labour, Licencing, and Regulation, USA. The dataset consists of 21 variables; we used the variable 5 that is new claims filed and variable 12 with total observation for each variable is 58. The dataset was also used by [15]. The third data deal with upheld most frequent complaints such as nonrenewal of insurance, and no fault claims commonly against vehicle insurance company over two-year period as a proportion of their overall business. The dataset was also used by Khan et al. [21]. The descriptive summary of all three datasets is shown in Table 7 and consists of sample size n, minimum claim x0, maximum claim x, lower Q1 and upper Q3, quartile deviations, mean , median , standard deviation σ, measures of skewness S, and kurtosis K. Total time on test (TTT) plots of the datasets is illustrated in Figure 13, revealing that the first two datasets have increasing hazard rate function, while the third dataset has decreasing (increasing) hazard rate function.
Table 7
Descriptive summary of datasets.
n
x0
Q1
x˜
x¯
σ
Q3
xn
Sk
K
Data 1
58
29.000
53.250
63.50
70.670
32.645
74.750
222.00
2.436
10.622
Data 2
58
102.00
133.00
153.00
155.30
31.899
176.00
267.00
0.608
4.0694
Data 3
89
1.0480
2.6160
7.0940
14.079
25.266
15.374
204.17
5.312
37.969
Figure 13
TTT Plots of EBellE of data 1–4.
The comparative study is carried out with several modified well-established exponential models, namely, exponentiated exponential Poisson (EEP) [35], alpha power exponentiated exponential (APEE) [15], Transmuted generalized exponential (TGE) [36], gamma exponentiated exponential (GEE) [37], exponential (E), exponentiated exponential (EE), Marshal Olkin exponential (MOE) [38], exponentiated Weibull (EW) [39], odd Weibull exponential (OWE) [19], Weibull (W), Kumaraswamy exponential (KE) [40], beta exponential (BE) [41], Tope Leone exponential (TLE) [42], and Nadarajah Haghigh (NH) [43] distributions.All statistical computational work is carried out using R-programming language. Table 8 shows the MLEs and standard errors (S.E) of the estimates of the fitted models of the data sets. Table 9 demonstrated the commonly used well-known model selection information criterion, namely, AIC, CAIC, BIC, and HQIC with important measures including Anderson–Darling (A), Cramér–von Mises (W), and Kolmogrov–Smirnov (K–S) test and p value of all three datasets. The analysis of the datasets revealed the proposed three-parameter EBellE model, outperforming compared to several well established models. A model having higher p values and least information criterion and A and W, and the K-S value is considered as best models among all other comparative models. TTT plots of the respective datasets are shown in Figure 13. Likewise, plots of the estimated pdf, cdf, hrf, and sf for the four datasets are provided in Figures 14–17. Additionally, PP-plots are presented in Figure 18.
Table 8
Estimated parameters and S.Es of insurance data.
Dist.
Parameter
Data 1
Data 2
Data 3
Estimates
S.E
Estimates
S.E
Estimates
S.E
EBellE
α^
0.028
0.007
0.0097
0.002
0.022
0.010
θ^
10.86
3.442
13.67
3.392
1.174
0.124
λ^
1.34
0.325
2.334
0.345
1.510
0.274
EEP
α^
0.032
0.007
0.015
0.002
0.026
0.011
β^
11.65
3.794
18.01
4.357
1.087
0.119
λ^
3.183
1.410
4.326
1.456
4.400
1.496
APEE
α^
0.032
0.007
0.020
0.007
0.026
0.010
β^
0.040
0.057
0.008
0.024
0.012
0.018
γ^
11.48
3.714
42.11
32.12
1.087
0.119
TGE
α^
0.041
0.006
0.028
0.007
0.044
0.010
β^
0.620
0.262
0.922
0.383
0.772
0.169
λ^
13.63
4.445
80.09
65.40
0.938
0.117
GEE
α^
0.051
0.013
0.132
0.004
0.055
0.010
β^
11.97
8.136
2.819
0.466
1.502
0.738
λ^
1.354
1.139
19.49
0.875
0.557
0.277
EE
α^
0.048
0.006
0.043
0.017
0.063
0.010
β^
16.08
5.250
405.2
903.6
0.837
0.117
MOE
α^
0.066
0.008
0.035
0.003
0.028
0.011
a^
72.13
41.02
160.9
57.75
0.213
0.106
OWE
α^
0.003
0.001
0.107
0.068
0.003
0.001
a^
14.28
7.280
0.011
0.005
11.11
2.873
b^
1.911
0.180
0.245
0.156
0.763
0.055
W
α^
0.585
0.081
0.642
0.083
0.127
0.028
β^
40.33
19.12
24.49
9.451
0.823
0.061
KE
α^
0.073
0.023
0.127
0.003
0.008
0.005
a^
34.93
27.33
0.081
0.042
0.819
0.074
b^
0.543
0.247
0.049
0.007
6.133
3.409
BE
α^
0.076
0.025
0.020
0.003
0.015
0.017
a^
33.00
24.58
34.708
9.900
0.818
0.107
b^
0.515
0.235
2.146
0.685
3.871
4.198
TLE
α^
0.024
0.003
0.011
0.001
0.031
0.005
a^
15.98
5.190
17.35
4.216
0.838
0.117
NH
α^
0.003
0.001
0.003
0.001
0.229
0.070
β^
3.900
0.874
2.022
0.347
0.549
0.076
E
α^
0.014
0.002
0.006
0.001
0.071
0.008
Table 9
The statistics , AIC, CAIC, BIC, HQIC, A, W, K-S, and p value for datasets.
Dist.
−2ℓ^
AIC
CAIC
BIC
HQIC
A∗
W∗
K.S
P value
Data 1
EBellE
264.79
535.57
536.01
541.75
537.98
0.603
0.108
0.096
0.655
EEP
265.31
536.62
537.06
542.80
539.03
0.701
0.127
0.099
0.619
APEE
265.31
536.62
537.06
542.80
539.03
0.703
0.128
0.100
0.610
TGE
266.36
538.71
539.16
544.89
541.12
0.893
0.164
0.102
0.576
GEE
267.65
541.31
541.75
547.49
543.71
1.132
0.209
0.118
0.395
EE
267.49
538.97
539.19
543.09
540.58
1.090
0.201
0.113
0.448
MOE
274.32
552.64
552.85
556.76
554.24
2.218
0.400
0.140
0.204
OWE
572.33
569.93
570.37
576.11
572.33
3.312
0.608
0.187
0.034
W
291.24
586.47
586.69
590.59
588.08
2.065
0.380
0.332
0.000
KE
266.73
539.46
539.90
545.64
541.86
0.991
0.181
0.115
0.430
BE
266.65
539.30
539.74
545.48
541.70
0.975
0.178
0.113
0.448
TLE
267.49
538.97
539.19
543.09
540.58
1.091
0.202
0.113
0.445
NH
295.63
595.27
595.48
599.39
596.87
2.781
0.511
0.371
0.000
E
304.97
611.93
612.01
613.99
612.74
1.755
0.324
0.387
0.000
Data 2
EBellE
281.25
568.51
568.95
574.69
570.91
0.1887
0.0184
0.0523
0.9973
EEP
284.62
575.24
575.68
581.42
577.64
0.3178
0.0368
0.1089
0.4967
APEE
281.86
569.71
570.15
575.89
572.12
0.4017
0.0497
0.0795
0.8565
TGE
281.56
569.12
569.57
575.30
571.53
0.3841
0.0464
0.0840
0.8078
GEE
281.33
568.66
569.11
574.84
571.07
0.2141
0.0188
0.0545
0.9954
EE
283.74
571.49
571.71
575.61
573.09
0.7022
0.0953
0.1261
0.3146
MOE
291.12
586.24
586.46
590.36
587.85
0.2046
0.0197
0.1687
0.0737
OWE
294.13
594.27
594.71
600.45
596.68
1.3843
0.1875
0.1481
0.1571
W
291.24
586.47
586.69
590.59
588.08
2.0654
0.3799
0.3320
0.0001
KE
357.54
721.08
721.52
727.26
723.49
0.2036
0.0170
0.5291
0.0000
BE
282.53
571.05
571.50
577.24
573.46
0.2880
0.0309
0.0827
0.8220
TLE
293.44
590.88
591.10
595.00
592.49
0.2913
0.0314
0.1756
0.0560
NH
341.65
687.30
687.51
691.42
688.90
0.1982
0.0161
0.4992
0.0001
E
350.62
703.23
703.30
705.29
704.03
0.2091
0.0182
0.4818
0.0001
Data 3
EBellE
313.42
632.85
633.13
640.31
635.86
1.265
0.185
0.113
0.188
EEP
314.86
635.73
636.01
643.19
638.74
1.410
0.205
0.114
0.182
APEE
314.86
635.73
636.01
643.19
638.74
1.410
0.204
0.114
0.182
TGE
318.91
643.81
644.09
651.28
646.82
1.802
0.262
0.118
0.156
GEE
322.69
651.39
651.67
658.85
654.39
2.191
0.323
0.121
0.134
EE
323.55
651.10
651.24
656.08
653.11
2.271
0.335
0.125
0.114
MOE
316.42
636.83
636.97
641.81
638.84
1.156
0.161
0.127
0.104
OWE
322.55
651.10
651.38
658.57
654.11
1.979
0.286
0.138
0.061
W
320.41
644.82
644.96
649.80
646.83
1.861
0.269
0.126
0.110
KE
321.66
649.32
649.60
656.79
652.33
2.030
0.296
0.118
0.152
BE
323.12
652.24
652.53
659.71
655.25
2.226
0.328
0.117
0.162
TLE
323.55
651.10
651.24
656.08
653.11
2.271
0.335
0.125
0.113
NH
315.90
635.80
635.94
640.78
637.81
1.286
0.182
0.122
0.132
E
324.38
650.76
650.80
653.25
651.76
2.232
0.329
0.162
0.017
Figure 14
Plots of estimated density, estimated cdf, estimated hrf, and failure rate for data 1.
Figure 15
Plots of estimated density, estimated cdf, estimated hrf, and failure rate for data 2.
Figure 16
Plots of estimated density, estimated cdf, estimated hrf, and failure rate for data 3.
Figure 17
Plots of estimated density, estimated cdf, estimated hrf, and failure rate for data 4.
Figure 18
P-P plots of EBellE of data 1–4.
8.2. GASP
Recently, Almarashi et al. [29] designed a GASP under Marshall–Olkin–Kumaraswamy exponential distribution by using the data of breaking strength of carbon fibers. The data consist the 50 observed values with mean (1.975) and median (1.190) breaking strength of carbon fibers, respectively. Under the K–S test, the maximum distance between actual and fitted yielded as 0.0681 with p value 0.9743 under Marshall–Olkin–Kumaraswamy exponential distribution. We used the same data as data-4, and our proposed three-parameter EBellE model is slightly better fit compared to four-parameter Marshall–Olkin–Kumaraswamy exponential distribution [29] as K-S test as 0.0680 with improved p value as 0.9749. The estimated parameters (SEs), namely, = 0.3913 (0.1308), = 0.9088 (0.2114), and = 0.3431 (0.5766). Table 10 shows the GAPS under the EBellE model at MLEs' values showing minimum g and c when r = 5 and r = 10, with a1 = 0.5 and 1. The analysis of the data yielded from Table 10, with β=0.25, a1 = 1, and r2 = 4 and taking r = 5, there are 7 groups or 35 (7 × 5=35); total units are needed for lifetime testing. While, on the contrary, significant reduction can be observed in groups or number of units to be tested under the identical circumstances when r = 10; a total of 2 groups or 20 (2 × 10=20) item are needed for life testing. Here, we prefer the group size as 10. When the true median life increases, the number of groups decreases and the operating characteristics values increases under the EBellE model.
Table 10
GASP under the EBellE model, and , showing minimum g and c Data 4.
β
r2
r=5
r=10
a1=0.5
a1=1
a1=0.5
a1=1
g
c
p(a)
g
c
p(a)
g
c
p(a)
g
c
p(a)
0.25
2
–
–
–
–
–
–
–
–
–
–
–
–
4
38
3
0.9808
7
3
0.9668
3
3
0.9585
2
4
0.9547
6
7
2
0.9766
7
3
0.9908
3
3
0.9880
1
3
0.9678
8
7
2
0.9887
3
2
0.9726
2
2
0.9686
1
3
0.9860
0.1
2
–
–
–
–
–
–
–
–
–
–
–
–
4
63
3
0.9683
73
4
0.9850
13
4
0.9763
5
5
0.9800
6
12
2
0.9602
12
3
0.9842
5
3
0.9800
3
4
0.9836
8
12
2
0.9806
4
2
0.9636
3
2
0.9533
2
3
0.9721
0.05
2
–
–
–
–
–
–
–
–
–
–
–
–
4
82
3
0.9590
95
4
0.9806
16
4
0.9709
7
5
0.9722
6
15
2
0.9505
15
3
0.9804
7
3
0.9722
4
4
0.9782
8
15
2
0.9758
5
2
0.9547
3
2
0.9533
2
3
0.9721
0.01
2
–
–
–
–
–
–
–
–
–
–
–
–
4
–
–
–
146
4
0.9703
25
4
0.9549
10
5
0.9605
6
125
3
0.9840
23
3
0.9700
10
3
0.9605
5
4
0.9728
8
23
2
0.9632
23
3
0.9883
10
3
0.9842
3
3
0.9585
Remark: a large sample size in required cells contains hyphens (–).
8.3. Concluding remarks
We introduced and documented the new flexible family of distributions called exponentiated Bell-G family. We also derived general mathematical properties of the proposed family, namely, linear representation of the density, random variable generation, reliability properties, ordinary moments, generating function, probability weighted moment, entropies, order statistics, reverse order statistics, entropies measures, upper records values, stochastic ordering, and estimation of parameters. We also illustrated the important actuarial measures and design of GASP. We also implemented the new proposed generator to the four real datasets by taking exponential distribution as a special case. The analysis of the data yielded that the new generator is found to be superior compared to their counterparts. [44].