This paper investigated consequences of measurement error in the pretest on the estimate of the treatment effect in a pretest-posttest design with the analysis of covariance (ANCOVA) model, focusing on both the direction and magnitude of its bias. Some prior studies have examined the magnitude of the bias due to measurement error and suggested…

The authors empirically examined whether the validity of a residualized dependent variable after covariance adjustment is comparable to that of the original variable of interest. When variance of a dependent variable is removed as a result of one or more covariates, the residual variance may not reflect the same meaning. Using the pretest-posttest…

Growth is estimated most accurately by procedures involving the pretest-posttest difference, and for practical purposes all estimates involving this difference have approximately equal accuracy. In particular, the simple difference between pretest and posttest scores seems about as accurate as any other estimate, easier to compute, and meaningful…

Problems in measuring change abound. For many purposes, a pretest score is best treated as any other measure obtained at the time of the pretest. Where appropriate, regression analyses that treat the pretest no differently from other independent variables, and the posttest as the dependent variable avoid many difficulties introduced by gain…

Livingston's reliability coefficients and Harris' indices of efficiency were computed along with the classical internal consistency coefficients, KR-20's (Kuder-Richardson internal consistency coefficient), for 678 criterion-referenced tests in the A through E levels of an individualized mathematics program. The coefficients were carefully studied…

The pretest-posttest design referred to as Design 2 by Campbell and Stanley (1963) is commonly used in educational research and evaluation. The tenability of the assumption of a zero population difference commonly used with this design is questioned. A nonzero population estimate based on the mean difference observed in test-retest reliability…

A total of 186 kindergarteners were pretested on number conservation and two cognitive style measures representing Kagan's impulsivity-reflectivity dimension and Santostefano's leveling-sharpening dimension. From this sample 72 nonconservers were assigned to one of three conservation training conditions: reversibility training, discrimination…

The accuracy with which regression models estimate treatment effects is dependent upon a number of conditions. The stability of the regression line (a function of sample size and correlation between pretest and posttest) is said to be the most important of these conditions. The utility of regression models is proportional to the size of the…

Two types of sensitivity indices were developed in this paper, one internal to the total test and the second external. To evaluate the success of these statistics the three criteria suggested for a satisfactory index of item quality were considered. The Internal Sensitivity Index appears to meet these demands. Certainly it is easily computed. In…

The relationship between physically and psychologically stressful experiences and the anxiety and self concept of 33 male and 11 female participants (aged 16-38 years) in a 23-day Colorado Outward Bound (OB) course was analyzed. It was hypothesized that the effects of the OB experience would: be the same for male and female participants; alter…

Two methods of reading instruction (homogeneous grouping and graded classes) are compared for 165 students in 8 rural North Dakota schools by raw gain scores, residual gain scores, and the analysis of covariance. (CK)