The Two-Way Analysis of Variance tests the equality of means of populations classified by two factors. It requires the data to be balanced (all factor combinations must have the same number of observations). The residuals and fitted values of the response are shown in Columns AA:AB.
At the Excel Menu (For Excel 2007, go to Add-ins first)
Choose ProcessMA > Statistics > ANOVA > Two-Way ANOVA
In Variable, select the column containing the response data (Numeric)
In Factor 1, select the column containing first factor levels (>=2 levels)
In Factor 2 , select the column containing second factor levels (>=2 levels)
Check Additive Model, if you want to fit the model without the interaction term
In Confidence Level, enter the desired confidence level for the confidence interval (Numeric, >0 & <1)
Check Show Boxplot, if you want to display boxplot of the data
Check Plot Residual, if you want to display residual plots
Click OK
You conducted an experiment to study how well organisms multiple in different temperatures and in the presence of different catalysts. You prepared 18 dishes of organisms and placed them at three different temperatures and added three different types of catalyst. You recorded the number of organism in each dish after 10 days. You want to use the Two-Way ANOVA to test if there is significant evidence of main and interactions effects.
Open data worksheet by choosing ProcessMA > Tools > Data
Choose ProcessMA > Statistics > ANOVA > Two-Way ANOVA
In Variable, select L - Organism
In Factor 1 , select M - Temperature
In Factor 2 , select N - Catalyst
Click OK
For a desired a = 0.05, there is no significant evidence for the temperature and temperature*catalyst interaction effects. There is significant evidence for the catalyst main effects on the growth of the organisms since p = 0.002 < a. From the confidence interval, it suggests that catalyst B promotes the growth of the organism more than the other two.
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