Complete the following steps to specify the columns of data that you want to analyze.
- In Response, enter the observed time for each observation. This value is either the time until the event of interest or the censoring time. The column must be numeric.
- In Censoring column (optional), enter a column that contains two distinct values. One value indicates a censored observation. The other value indicates the event of interest. A response time is censored if the subject does not experience the event of interest before the study ends, or if the subject leaves the study before they experience the event. You can specify which value indicates a censored observation in Censoring
value. By default, the lowest numeric value or the lowest ASCII value for text columns is the censoring value.
- In Entry time
(optional), specify the entry time for each observation. The column must be numeric and the same length as the column in Response. The entry times must be less than or equal to the response times. If you do not specify a column, Minitab uses 0 for the entry time for all observations.
Use entry times to model left-truncated data. A time is left-truncated when the subject enters after time 0. For example, you don't include patients on a waiting list for an organ transplant until an organ is available for transplant.
- In Continuous
predictors, enter the columns of numeric data that may explain or predict changes in the response. The predictors are also called X variables.
- In Categorical predictors, enter the categorical classifications or group assignments, such as a type of treatment, that may explain or predict changes in the response. The predictors are also called X variables.
- In Stratification variables
(optional), enter a column to fit a stratified model. Each unique combination of values in the columns that you specify defines a stratum. A stratified model estimates a baseline hazard rate for each strata but uses the same estimates for the effects of the predictors. You can have up to two stratification variables.
In this worksheet, Time is the response and contains the number of years between the first treatment and either the patient's death or the end of the study. Death is the censoring variable and indicates whether the patient died. A value of "No" indicates a censored observation where the subject did not experience the event before the end of the study. Age is a continuous predictor and Stage is a categorical predictor. The predictors may explain differences in survival time. The first row of the worksheet shows that the first patient had stage I of larynx cancer, started treatment at age 77, and was in the study for 0.6 years until they died.
| C1 |
C2 |
C3 |
C4 |
| Stage |
Time |
Age |
Death |
| I |
0.6 |
77 |
Yes |
| I |
1.3 |
53 |
Yes |
| I |
2.4 |
45 |
Yes |
| I |
2.5 |
57 |
No |
| I |
3.2 |
58 |
Yes |
| I |
3.2 |
51 |
No |
