| CONCOV - Covariance Curve Estimation |
Whereas the dimensionality assessment procedures—DIMTEST, HCA/CCPROX,
and DETECT—examine dimensionality
by averaging over all examinee ability levels, CONCOV
nonparametrically estimates the conditional covariance curve for
each item pair as a function of the underlying composite latent
ability best measured by the total test score. The resulting
curves as well as their confidence intervals are graphically
displayed for easy evaluation by the user. CONCOV presumes
dichotomous item scoring. Such nonparametric estimated
conditional covariance curves and nonparametric estimates of the
item response functions can together be used to estimate a
non-unidimensional IRT model for test data when unidimensionality
fails.
System Requirements
This software is a DOS based program, which will run in the Windows environment, unless specific exceptions are noted. If you experience difficulty opening this software, please refer to the following support page on the Microsoft website:
Microsoft Support Article ID# 324767 - "Error message when you install or start an MS-DOS or 16-bit Windows-based program"
If you are unable to get this software to run on your machine, or if you have questions before purchasing the program, please contact our technical support department.
Multiple License Purchases
Multi-license purchasers click here for information on discounts.
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