Example of the With Control, Dunnett’s Test
This example uses the Oneway platform to illustrate Dunnett’s test with a control group.
1. Select Help > Sample Data Folder and open Big Class.jmp.
2. Select Analyze > Fit Y by X.
3. Select weight and click Y, Response.
4. Select age and click X, Factor.
5. Click OK.
6. Click the Oneway Analysis red triangle menu and select Compare Means > With Control, Dunnett’s.
7. Select 12 as the age to use as the control group.
Tip: Click a point in the control group to highlight it in the scatterplot before selecting the Compare Means > With Control, Dunnett’s option. The test uses the selected group as the control group.
8. Click OK.
Figure 6.19 Example of With Control, Dunnett’s Comparison Circles
Using the comparison circles or the results in the LSD Threshold Matrix, you can conclude that level 17 is the only level that is significantly different from the control level of 12.
Tip: To obtain a one-sided test, select the Dunnett’s Lower option or the Dunnett’s Upper option in the red triangle menu next to Comparisons with a control using Dunnett’s Method.