Open AccessIMPOSSIBLE SCORES RESULTING IN ZERO FREQUENCIES IN THE ANCHOR TEST: IMPACT ON SMOOTHING AND EQUATING
Author(s) -
Puhan Gautam,
Davier Alina,
Gupta Shaloo
Publication year - 2008
Publication title -
ets research report series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.235
H-Index - 5
ISSN - 2330-8516
DOI - 10.1002/j.2333-8504.2008.tb02096.x
Subject(s) - equating , akaike information criterion , statistics , mathematics , smoothing , zero (linguistics) , raw score , econometrics , raw data , linguistics , philosophy , rasch model
Equating under the external anchor design is frequently conducted using scaled scores on the anchor test. However, scaled scores often lead to the unique problem of creating zero frequencies in the score distribution because there may not always be a one‐to‐one correspondence between raw and scaled scores. For example, raw scores of 17 and 18 may correspond to scaled scores of 150 and 153, thereby creating zero frequencies for scaled scores of 151 and 152. These gaps in the frequency distribution may adversely impact smoothing and equating. This study examines the effect of these zero frequencies on log‐linear smoothing (Holland & Thayer, 1987) of score distributions and final equating results. Results suggest that although smoothing is significantly affected by the presence of these zero frequencies, as indicated by the likelihood‐ratio chi‐square, Akaike information criterion (Akaike, 1977), and Freeman‐Tukey deviates, the impact on the actual equating results is minimal.