Worksheet Structure for Regression with Life Data
main topics      

The basic worksheet structure for regression with life data is three columns, although you may have more than three. The three columns in the worksheet:

·    the response variable (failure times)

·    censoring indicators (for the failure times, if needed)

·    predictor variables

-    For Accelerated Life Testing, enter one or two predictor columns. The first predictor column contains various levels of an accelerating variable. For example, an accelerating variable may be stresses or catalysts whose levels exceed normal operating conditions. The second predictor column can contain either various levels of a second accelerating variable or various levels of a factor.

-    For Regression with Life Data, enter one or more predictor columns. These predictor variables may be treated as factors or covariates in the model. For more information, see How to specify the model terms.

Structure each column so that it contains individual observations (one row = one observation), or unique observations with a corresponding column of frequencies. Frequency columns are useful when you have large numbers of data with common failure and censoring times, and identical predictor values.

Here is the same worksheet structured both ways:
 

Text categories (factor levels) are processed in alphabetical order by default. If you wish, you can define your own order - see Ordering Text Categories.

The way you set up the worksheet depends on the type of censoring you have, as described in Failure times.

Minitab automatically excludes all observations with missing values from all calculations.