OBJECTIVE: Measurements from health-related quality-of-life (HRQoL) studies, although usually of an ordered categorical nature, are typically treated as continuous variables, allowing the calculation of mean values and the administration of parametric statistics, such as t-tests. We investigated whether parametric, compared to nonparametric, analyses of ordered categorical data may lead to different conclusions. STUDY DESIGN AND SETTING: HRQoL data were obtained from patients with a diagnosis of asthma (n=192) and chronic obstructive pulmonary disease (COPD; n=88) at two time points. The impact of the group factor (asthma vs. COPD) and the time factor (t1 vs. t2) on HRQoL was analyzed with a metric approach (repeated measures ANOVA) and two ordinal approaches (each with a nonparametric repeated measures ANOVA). RESULTS: Using the metric approach, a significant effect of "group" (P=0.0061) and "time" (P=0.0049) on HRQoL was found. The first ordinal approach (ranked total score) still showed a significant effect for "group" (P=0.0033) with a worse HRQoL for patients suffering from COPD. In the second approach (ranks for each HRQoL item and summed ranks), there were no significant effects. CONCLUSION: Applying simple parametric methods to ordered categorical HRQoL scores led to different results from those obtained with nonparametric methods. In these cases, an ordinal approach will prevent inappropriate conclusions.
OBJECTIVE: Measurements from health-related quality-of-life (HRQoL) studies, although usually of an ordered categorical nature, are typically treated as continuous variables, allowing the calculation of mean values and the administration of parametric statistics, such as t-tests. We investigated whether parametric, compared to nonparametric, analyses of ordered categorical data may lead to different conclusions. STUDY DESIGN AND SETTING: HRQoL data were obtained from patients with a diagnosis of asthma (n=192) and chronic obstructive pulmonary disease (COPD; n=88) at two time points. The impact of the group factor (asthma vs. COPD) and the time factor (t1 vs. t2) on HRQoL was analyzed with a metric approach (repeated measures ANOVA) and two ordinal approaches (each with a nonparametric repeated measures ANOVA). RESULTS: Using the metric approach, a significant effect of "group" (P=0.0061) and "time" (P=0.0049) on HRQoL was found. The first ordinal approach (ranked total score) still showed a significant effect for "group" (P=0.0033) with a worse HRQoL for patients suffering from COPD. In the second approach (ranks for each HRQoL item and summed ranks), there were no significant effects. CONCLUSION: Applying simple parametric methods to ordered categorical HRQoL scores led to different results from those obtained with nonparametric methods. In these cases, an ordinal approach will prevent inappropriate conclusions.
Authors: Pasquale Anselmi; Giulio Vidotto; Ornella Bettinardi; Giorgio Bertolotti Journal: Health Qual Life Outcomes Date: 2015-02-07 Impact factor: 3.186
Authors: Alberto Carmona-Bayonas; Caterina Calderón; Raquel Hernández; Ana Fernández Montes; Beatriz Castelo; Laura Ciria-Suarez; Mónica Antoñanzas; Jacobo Rogado; Vilma Pacheco-Barcia; Elena Asensio Martínez; Alejandra Ivars; Francisco Ayala de la Peña; Paula Jimenez-Fonseca Journal: NPJ Breast Cancer Date: 2021-07-13