A generalizability study of the Eating Attitudes Test (EAT-12) in non-clinical adolescents

Trajectory analysis of discrete goal-directed pointing movements: How many trials are needed for reliable data?

A powerful tool in motor behavior research is trajectory analysis of discrete goal-directed pointing movements. The purpose of the present analysis was to estimate the minimum number of trials per participant required to achieve the conventional level of reliability for trajectory analysis. We analyzed basic measurements of movement and three common methods of trajectory analysis within the framework of generalizability theory. Generalizability studies were used to decompose the total variance of these variables into the percent contributions from person, trial, and the person-by-trial interaction. Decision studies were then used to determine the minimum number of trials required to achieve the conventional level of reliability. The number of trials per participant needed for reliable data of discrete goal-directed pointing movements depended on the dependent variable-for example, reaction times required six or ten trials, movement times required three trials, and constant error required 47 trials. For trajectory analysis, ten or fewer trials were required for reliable dependent variables during the first half of the movement (up to peak velocity or 70% of the displacement). The number of trials required for the second half of the movement rapidly increased to 47 trials at movement termination. This increase in the number of trials required for reliable analysis of the second half of the movement was indicative of online control. Finally, correlation analysis was performed with simulated correlations on subsets of trials, and all 32 trials were required. However, 18 trials might be used without a practically significant change in the correlations.

The eating attitudes test: twenty-five years later

This manuscript reviews the literature involved with the Eating Attitudes Test (EAT), first developed in the late 1970s as a self-report, indicative of the symptoms of eating disorders. The EAT has good psychometric properties of reliability and validity, and reasonable sensitivity and specificity for the eating disorders, but very low positive predictive value because eating disorders are relatively uncommon. In addition they exist on a continuum, because of denial and social desirability, the results of a self-report instrument may be affected. A very large literature has documented the use of the EAT in a variety of cultures. It is used to screen eating disturbances in general as the first part of a two-part diagnostic screen, as an ability to compare across groups and to measure change between groups and over time.