Visual Analysis of Variance allows the user to manipulate the variability within and between groups in a one-way ANOVA to visually see the effect on the F statistic. The online lecture is supported by two types of assignments: 1) Online computer-graded homework, and 2) A pdf file that gives students the opportunity to do handwritten homework problems with answer keys.
Visualize the relationship between variability within groups and the variability in means and how these affect the value of the F-statistic in the analysis of variance.
Target Student Population:
Students in a course covering Analysis of Variance.
Prerequisite Knowledge or Skills:
Students will need to have been introduced to the idea of ANOVA, significance testing, and the F distribution.
Type of Material:
It can be used in class to illustrate concepts related to ANOVA. It can also be used by students as a resource or with directed questions from an instructor.
Web Browser, Java, Flash.
To access additional online lecture you will need Adobe Acrobat, and possibly to download some plugins.
Evaluation and Observation
The author is very clear that this applet is not a numerical calculator, but instead demonstrates the relations "among important concepts" visually. It does an excellent job of this visual representation. The material clearly illustrates how within- and between-group variability combine to change the value of the F statistic.
While the material successfully illustrates the relationship between within- and between-group variability, one additional piece that would make the material more complete is illustrating the effect of sample size as well.
Potential Effectiveness as a Teaching Tool
Students can easily "discover" the effects of small ->large within group variability on the F-statistic, and check their intuitions. The material is fairly straightforward and easy for students to understand with very little introduction.
If an instructor wants to use the material for more than just a quick in class demonstration, it will take some creativity on the part of the instructor to get students to use it effectively. There is not a great deal you can do with this applet - it has only one quick idea to get across, but it is a wonderful visualization of that idea.
Ease of Use for Both Students and Faculty
The applet is quite easy to use and has very clear instructions. The flash program is of very high design quality and is very visually appealing.
Changing the variability within groups with the yellow buttons is a bit awkward. It would be preferable to grab the edges of the red icons to resize them.
Other Issues and Comments:
The link to " Do Computer-graded Online Homework" does not appear to work, nor does the "Do Handwritten Homework with Answer Key", so perhaps these should be removed now that the course is no longer active.