Psychophysical parameters of the perception of orally-retained liquid bulk

Bulk of liquid held in the mouth may be judged on its subjective volume. Over the range I ml-31 ml, scaling by the constant method and by ratio estimation yielded a Weber fraction which was not constant and decreased with stimulus magnitudes and a psychophysical power function with an exponent of 0.96. A “negative threshold” effect is reported.     

An empirical study of the normality and independence of errors of measurement in test scores

An empirical study of test scores shows the variance of the errors of measurement to be significantly associated with true score in each of four groups studied; it also shows the distribution of the errors of measurement to be significantly skewed in three of these four groups. The mathematical rationale underlying the statistical treatment is presented. Standard error formulas are given for making the necessary significance tests.This research was in part carried out under Contracts Nonr-2214(00) and Nonr-2752(00) with the Office of Naval Research, Department of the Navy.     

Use of true-score theory to predict moments of univariate and bivariate observed-score distributions

Formulas are derived for using the available item statistics and score statistics on a test to estimate the moments of the score distribution of a lengthened (or shortened) form of the same test. Other formulas are derived for estimating the bivariate moments of the scatterplot between two parallel test forms using only the data available on either form alone. An empirical study is made showing in each case satisfactory agreement between the theoretical values predicted from the formulas and the values actually observed. These results suggest the utility of the true-score model used in deriving the formulas.This work was supported by contract Nonr-2752(00) between the Office of Naval Research and Educational Testing Service. Reproduction in whole or in part for any purpose of the United States Government is permitted.