If your response has exactly two levels, the Inverse Prediction option enables you to request an exact inverse prediction. You are given the x value corresponding to a given probability of the lower response category, as well as a confidence interval for that x value.
To use the Inverse Prediction option, proceed as follows:
|
1.
|
|
2.
|
Select Analyze > Fit Y by X.
|
|
3.
|
|
4.
|
Notice that JMP automatically fills in Count for Freq. Count was previously assigned the role of Freq.
|
5.
|
Click OK.
|
|
6.
|
|
7.
|
Type 0.95 for the Confidence Level.
|
|
8.
|
Select Two sided for the confidence interval.
|
|
9.
|
Request the response probability of interest. Type 0.5 and 0.9 for this example, which indicates you are requesting the values for ln (dose) that correspond to a 0.5 and 0.9 probability of being cured.
|
|
10.
|
Click OK.
|
Figure 7.124 Inverse Prediction Window
Figure 7.125 Example of Inverse Prediction Plot
The estimates of the x values and the confidence intervals are shown in the report as well as in the probability plot. For example, the value of ln (dose) that results in a 90% probability of being cured is estimated to be between -0.526 and 0.783.