I am using Excel to do some ANOVA calculations. Say that we have one
independent variable A, where we have 10 samples for each level of A.
Then a one way ANOVA tells us whether there is a significant
difference
in the means of A's levels.
If I add a second independent variable B with 2 levels to the data
set,
and I assign 5 samples from each level of A to each level of B, then
each cell of the 2 dimensional table will be made up of 5 samples.
When I perform a two
way ANOVA in Excel, it gives us 3 values, then means of the samples
grouped
by factor A, the means grouped by factor B, and the interaction
effect.
However the p value I get for the samples grouped by A in two way
ANOVA,
is different than the p value of the one way ANOVA on A that I
performed
at the beginning. Why is this? Shouldn't the p-values be identical?
Aren't
we testing the same hypothesis in each case?
Thank you very much.
.
.
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