The focus of this study was on the visual analysis of time series data for evaluating educational programs. Two characteristics of the data--changes in slope and variability--and two characteristics of evaluation--training in data utilization and the use of aimlines/decision rules--were manipulated. A total of 51 students and/or teachers in…

The agreement between visual analysis and the results of the split-middle method of trend estimation was examined using a set of 24 stimulus graphs and 30 raters. Results revealed poor agreement between the two methods, and low sensitivity, specificity, and predictive ability for visual analysis in relation to statistical inferences. (JDD)