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Factor Analysis for Clustered Observations

Published online by Cambridge University Press:  01 January 2025

N. T. Longford*
Affiliation:
Educational Testing Service
B. O. Muthén
Affiliation:
University of California, Los Angeles
*
Requests for reprints should be sent to N. T. Longford, 21-T, Educational Testing Service, Rosedale Rd., Princeton, NJ 08541.

Abstract

Classical factor analysis assumes a random sample of vectors of observations. For clustered vectors of observations, such as data for students from colleges, or individuals within households, it may be necessary to consider different within-group and between-group factor structures. Such a two-level model for factor analysis is defined, and formulas for a scoring algorithm for estimation with this model are derived. A simple noniterative method based on a decomposition of the total sums of squares and crossproducts is discussed. This method provides a suitable starting solution for the iterative algorithm, but it is also a very good approximation to the maximum likelihood solution. Extensions for higher levels of nesting are indicated. With judicious application of quasi-Newton methods, the amount of computation involved in the scoring algorithm is moderate even for complex problems; in particular, no inversion of matrices with large dimensions is involved. The methods are illustrated on two examples.

Information

Type
Original Paper
Copyright
Copyright © 1992 The Psychometric Society

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