The Main Effects Plot plots means of factor levels. The reference line is the overall mean of the data. It is used to visualise the magnitudes of main effects.
1. Choose ProcessMA > Graphs > Main Effects 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 Main Effects Plot to visualise the growth of the organisms by temperature and catalysts.
1. Open worksheet ProcessMA > Tools > Data Files > Stat.xls.
2. Choose ProcessMA > Graphs > Main Effects Plot.
3. In Response, select P – Organism.
4. In Factors, select Q – Temperature, R – Catalyst.
5. Click OK.
Interpretation
The main effects plot suggests that the catalyst effects are larger than the temperature effects on the growth of organisms.