I would like to compare several samples using analysis of variance (ANOVA).
My input data looks like:
Mean SD n
0.6 +/-5.4 40
0.6 +/-0.2 7
0.4 +/-0.3 21
When I input this data in this ANOVA-online calculator, the result is
p = 0.984
- Since p > 0.05, does that mean "There were no statistically significant differences between group means"?
- I haven't yet understood the formulas cited below that online calculator, but I read that ANOVA computes a "grand mean" first. Is a grand mean computed with the formulas on that online calculator? If so, which of them?
Thank you very much for any help to understand this better.
EDIT: I understand that the common way to get a grand mean is to have all observations for each group, not just the means, sd and n. But how does this calculator do it? Isn't it computing some sort of grand mean, to which it compares the groups?
EDIT2: Reading on the subject a bit more, I found a source which confirms that using an average of the means weighted by sample count is an alternative way if the single samples are not available.