ERIC Number: ED368780
Record Type: RIE
Publication Date: 1994-Apr
Reference Count: N/A
A Revised Modified Parallel Analysis (RMPA) for the Construction of Unidimensional Item Pools.
Budescu, David V.; And Others
Modified Parallel Analysis (MPA) is a heuristic method for assessing "approximate unidimensionality" of item pools. It compares the second eigenvalue of the observed correlation matrix with the corresponding eigenvalue extracted from a "parallel" matrix generated by a unidimensional and locally independent model. Revised Modified Parallel Analysis (RMPA) generalizes MPA and alleviates some of its technical limitations. An important and useful feature is a new method for eliminating items which violate the test's unidimensionality. This is achieved by eliminating items, one at a time, to determine their contribution to the matrices' eigenvalues. We propose a test for detecting items with larger impact in the observed data set, and eliminating them. The new method was tested in several situations in which unidimensional item pools were "contaminated" by various proportions of items from a secondary pool. The results indicate that RMPA does an excellent job in detecting low (10%) and moderate (25%) levels of contamination, but fails in cases of maximal (50%) contamination. Eleven tables. (Contains 46 references.) (Author)
Publication Type: Reports - Evaluative; Speeches/Meeting Papers
Education Level: N/A
Sponsor: Office of Naval Research, Arlington, VA.
Authoring Institution: N/A
Identifiers: Eigenvalues; Modified Parallel Analysis; Revised Modified Parallel Analysis; Unidimensionality (Tests)
Note: Paper presented at the Annual Meeting of the National Council on Measurement in Education (New Orleans, LA, April 5-7, 1994).