JOANN KEYTON, Ph.D.
Distinguished Professor, Emerita
Department of Communication
North Carolina State University
Testing for Differences
Assessing Differences Between Groups
This interactive website provides a graphic view of the t-test (Note: this link can only be accessed from a web browser with Java enabled). The mean of the distribution shown in blue is fixed at 50, but you can vary the distribution of other groups shown in red. Try several different means for the red distribution. Notice how changing the mean changes the variance explained by the grouping, or nominal variable, which would be the independent variable. To help you understand the importance of the relative difference between the two distributions, imagine that the blue distribution represents females’ scores of communication apprehension and that the red distribution represents males’ scores of communication apprehension.
Ready to Review?
These websites, from Columbia University, are part of their QMSS e-Lessons project.
In addition, the educational YouTube channel Crash Course has a series of videos on statistics, including chi-square, t-test, and ANOVA. Addition statistical assessment resources can be found here.
What Statistic Do I Choose?
A great website from UCLA that helps you identify which statistical test to choose.
Have Data and Ready to Compute a t-Test?
This GraphPad website will let you enter your data for an independent sample t-test and compute your t-value.
Updated June 23, 2022