Assessing public health practice: application of ten core function measures of community health in six states.

Factor analysis, combined with an evaluation of item difficulty and discrimination, can provide useful insights in questionnaire development. In 1993, as part of a study to develop a questionnaire to assess performance of the core functions of public health at a community level, 370 local health departments (LHDs) in six states completed a 26-item questionnaire (94% response). This study describes factor analysis results after controlling for item difficulty and discrimination. Fifteen items had intermediate difficulty and fair-to-good discrimination. Factor analysis of these 15 items identified four factors. Three of these factors included items from more than one of the core functions. These findings pose an interesting question for future research: are the core functions of public health better conceived as three discrete, distinguishable factors or as three interlocking factors that form a single, seamless unit?