A Comprehensive Trial Of The Scree And Kg Criteria For Determining The Number Of Factors.

In most well designed researches larger substantive factors show a break in size from those of a trivial lower degree of variance, which are due to error and other sources. The only short test for the number of such factors that has been repeatedly supported by plasmode results is the scree. The present experiment extends this empirical testing of the scree by taking 15 plasmodes, which vary in (1) number of variables, (2) of factors, (3) degree of obliquity, from orthogonal cases on, (4) presence of simple structure, (5) presence of error, extending to factoring random numbers, and (6) size of communality. The results support the scree and show it superior to the Kaiser-Guttman unity root criterion. Apart from the scree itself, a brief examination is made of the reliability of its use in the hands of trained and untrained judges. A second evaluation of the intrinsic validity of the scree is made by examining internal consistency of item and parcel factoring, of different sampling of variables and of change of population. The result again supports its capacity to locate the correct number of factors within narrow limits.