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The Chain and Post‐Stratification Methods for Observed‐Score Equating: Their Relationship to Population Invariance
Author(s) -
Davier Alina A.,
Holland Paul W.,
Thayer Dorothy T.
Publication year - 2004
Publication title -
journal of educational measurement
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.917
H-Index - 47
eISSN - 1745-3984
pISSN - 0022-0655
DOI - 10.1111/j.1745-3984.2004.tb01156.x
Subject(s) - equating , statistics , mathematics , population , stratification (seeds) , econometrics , test (biology) , item response theory , demography , psychometrics , biology , ecology , seed dormancy , botany , germination , dormancy , sociology , rasch model
The Non‐Equivalent‐groups Anchor Test (NEAT) design has been in wide use since at least the early 1940s. It involves two populations of test takers, P and Q, and makes use of an anchor test to link them. Two linking methods used for NEAT designs are those (a) based on chain equating and (b) that use the anchor test to post‐stratify the distributions of the two operational test scores to a common population (i.e., Tucker equating and frequency estimation). We show that, under different sets of assumptions, both methods are observed score equating methods and we give conditions under which the methods give identical results. In addition, we develop analogues of the Dorans and Holland (2000) RMSD measures of population invariance of equating methods for the NEAT design for both chain and post‐stratification equating methods.