Essentially of unidimensionality for indicators in medical and behavior science measures: application of structural equations modeling

Aim and The unidimensionality feature of indicators of a construct is rooted in the classical test theory (CTT)، and in the context of CTT the term of being Homogeneity for items which was developed to measure a construct indirectly refers to this topic. Misunderstanding of the term has led many of researchers use exploratory factor analysis or Cronbach''s alpha procedures to investigating and determination of unidimensionality. While، none of these procedures were not design for this propose. Methods and Materials: Using the survey design، 468 mothers with multiphase cluster sampling method fill in the PSI-SF. The data was analysis by structural equating model using LISREL software. using structural equation modeling approach and related software’s، which provide investigation of distribution of residuals، one could test Presence or absence of the unidimensionality feature of indicators. This study، in addition to theoretical discussions، examined this issue with a sample of empirical data.