APPROXIMATING SCALE SCORE STANDARD ERROR OF MEASUREMENT FROM THE RAW SCORE STANDARD ERROR

Conditional estimates of the standard error of measurement (SEM) are n ecessary for conveying precision at a given score level. The reported metric for score level SEMs is almost always the raw score scale; howe ver, test interpretation typically centers on derived scores. A furthe r hindrance for utilizing the reported error information is the nonlin ear relation between raw scores and derived scores. To overcome these limitations, 2 relatively simple methods for estimating the conditiona l SEM for nonlinearly derived score scales are proposed. Empirical app lications of these methods indicate the derived score level SEM, like its raw score counterpart, varies across the score scales. However, un like the raw score scale SEMs, the variation displayed in derived scor e units tends to be erratic. The irregularity appears to be a conseque nce of integer conversions. The 2 proposed procedures produced fairly consistent estimates that tended to peak near the high end of the scal e and reach a minimum in the middle of the raw score scale.