This example uses the Car Physical Data.jmp sample data table to show an additional example of a logistic plot. Suppose you want to use weight to predict car size (Type) for 116 cars. Car size can be one of the following, from smallest to largest: Sporty, Small, Compact, Medium, or Large.
 1 Select Help > Sample Data Library and open Car Physical Data.jmp.
 2 In the Columns panel, right-click on the icon to the left of Type, and select Ordinal.
 3 Right-click on Type, and select Column Info.
 4 From the Column Properties menu, select Value Ordering.
 5 Move the data in the following top-down order: Sporty, Small, Compact, Medium, Large.
 6 Click OK.
 7 Select Analyze > Fit Y by X.
 8 Select Type and click Y, Response.
 9 Select Weight and click X, Factor.
 10 Click OK.
Example of Type by Weight Logistic Plot
In Example of Type by Weight Logistic Plot, note the following observations:
 • The first (bottom) curve represents the probability that a car at a given weight is Sporty.
 • The second curve represents the probability that a car is Small or Sporty. Looking only at the distance between the first and second curves corresponds to the probability of being Small.
 • As you might expect, heavier cars are more likely to be Large.
 • Markers for the data are drawn at their x-coordinate, with the y position jittered randomly within the range corresponding to the response category for that row.
If the x -variable has no effect on the response, then the fitted lines are horizontal and the probabilities are constant for each response across the continuous factor range. Examples of Sample Data Table and Logistic Plot Showing No y by x Relationship shows a logistic plot where Weight is not useful for predicting Type.
Examples of Sample Data Table and Logistic Plot Showing No y by x Relationship
Examples of Sample Data Table and Logistic Plot Showing an Almost Perfect y by x Relationship

Help created on 9/19/2017