An investigation of the psychometric evidence of CBM-R passage equivalence: Utility of readability statistics and equating for alternate forms

Claims have been made that grade appropriate curriculum-based measurement of reading (CBM-R) passages are of comparable difficulty and can be used interchangeably to monitor student progress. Empirical evidence to support claims of equivalence has been lacking. This research investigated the basis for making claims of equivalence. The use of readability statistics to justify passage equivalence was found to be lacking. Using a general measurement model for congeneric tests, CBM-R passages were found to measure a single latent factor with a high degree of reliability. However, evidence indicated that the raw scores, words read correctly per minute, across passages did not provide equivalent measurements. Statistical equating was investigated as an approach to overcome the lack of equivalence with promising results.