Complete the following steps to specify the columns of data that you want to analyze.
- In Response, enter the column of ordinal data that you want to explain or predict. An ordinal response has three or more outcomes that have an order, such as low, medium, and high.
- In Frequency
(optional), enter the column that contains the number of times that each response and predictor combination occurred.
- In Model, enter the terms that may explain or predict changes in the response. You can include continuous or categorical variables. For more information on specifying crossed or nested terms, go to Specifying model terms for ordinal logistic regression.
- In Categorical predictors
(optional), specify which of the variables in the model are categorical classifications or group assignments, such as type of raw material. Minitab assumes that all variables in the model are continuous predictors (covariates) unless you specify them as factors here. Continuous predictors are modeled as covariates and categorical predictors are modeled as factors.
In this worksheet, Survival is the response and indicates the length of time that a sample of hatched salamanders live (1 = <10 days, 2 = 10–30 days, and 3 = 31–60 days). Region is a categorical predictor (factor) and represents the region where the salamander is found. ToxicLevel is a continuous variable and represents the level of toxicity in the water where the salamander is found.
| C1 |
C2 |
C3 |
| Survival |
Region |
ToxicLevel |
| 1 |
A |
62 |
| 2 |
B |
46 |
| 3 |
A |
34 |
| 2 |
B |
56 |
In this worksheet, the response and predictor variables are the same as the previous example but the data also include a frequency variable. Frequency contains the count of salamanders that correspond to the combination of response and predictor values in each row. The first row in the worksheet shows that 3 salamanders survived less than 10 days in region A and were in water with a toxicity level of 62.
| C1 |
C2 |
C3 |
C4 |
| Survival |
Frequency |
Region |
ToxicLevel |
| 1 |
3 |
A |
62 |
| 2 |
1 |
B |
46 |
| 3 |
4 |
A |
34 |
| 2 |
2 |
B |
56 |
