What a great tool! An analysis of Variance (ANOVA) is a statistical method for making simultaneous comparisons between two or more means; a statistical method that yields values that can be tested to determine whether a significant relation exists between variables.
Well, now that we've got the dictionary definition out of the way....
An ANOVA gives you an estimate of whether two (or more) groups are likely to be mathematically related.
One of the favorite tricks of those who deliberately dissemble is collecting data from two (or more) groups and presenting results without checking to see if the groups are in fact are related. More commonly stated: they compare apples an oranges. ANOVA is *one* method of determining if the two groups should be related.
This tool allows the results of an anova to be calculated and displayed visually.
I spent ~ 30 minutes 'tinkering' with the program.