The Interactions Plot plots the means for each level of one factor with the levels of another factor. For more than two factors, a matrix of interaction plot is generated. It is used for identifying interactions between factors.
1. Choose ProcessMA > Graphs > Interactions Plot.
2. In Response, select the column containing the response data.
3. In Factors, select the column(s) containing the factor levels.
4. Click OK.
Note To select a column of data into a textbox, double-click on any of the column names shown in the list on the left of the dialog box while in the textbox.
Response: Numeric.
Factors: Text or Numeric; Must have the same number of data points as the Response.
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 Interactions Plot to assess the interactions in the data.
1. Open worksheet ProcessMA > Tools > Data Files > Stat.xls.
2. Choose ProcessMA > Graphs > Interactions Plot.
3. In Response, select P – Organism.
4. In Factors, select Q – Temperature, R – Catalyst.
5. Click OK.
Interpretation
The interaction plot suggests interactions as the lines are not parallel; meaning the effect of catalyst on the growth of organisms is dependant on the temperature.