Methods for Binary Fitted Line Plot

Find definitions and interpretation guidance for the Method table.

In This Topic

Link function
Response information

Link function

A link function maps the interval (0, 1) onto the whole real line. This guarantees that the predicted probability of an event using the model produces a number between 0 and 1. Minitab provides three link functions:

Logit
Normit (probit)
Gompit (complementary log-log)

Interpretation

Use the link function to find a model that best fits your data. Use the goodness-of-fit statistics to compare fits using different link functions. Certain link functions can be used for historical reasons or because they have a special meaning in a discipline.

One advantage of the logit link function is that it provides an estimate of the odds ratio for each predictor in the model.

Response information

Minitab displays this information about the response:

Variable: Name of the response variable
Value: Levels of the response variable
Count: Number of observations at each level of the response variable
Total: Number of nonmissing observations

The output also identifies which level of the response is the reference event.

Interpretation

Use the response information to examine how much data are in the analysis. Larger random samples with many occurrences of each level usually provide more accurate inferences about the population.

Also use the response information to determine which event is the reference event. Interpretation of statistics like coefficients and odds ratios depend on which event is the reference event.