Life Tables and Distributions
Creates Life Tables for censored data, and fits common distributions for survival or lifetime data. Specifying survival times: There are three ways to specify survival times. You can select one (continuous dependent) variable with survival times (e.g., number of weeks surviving), you can select two (continuous dependent) variables with start and stop times for each observation (the analysis will be performed on the differences between the two values, i.e., on the elapsed times), or you can select six (continuous dependent) variables containing dates. Specifically, these variables should contain the month (1 to 12), day (1 to 31), and year when the particular observation began (e.g., when a patient was admitted to the hospital), and the month, day, and year when the observation was terminated (due to death/failure or censoring, e.g., when a patient was dismissed from the hospital). While processing the data, Survival Analysis will compute the number of days that elapsed between dates and perform the analysis on this measure. Note that if the value of the year is less than 100, STATISTICA will automatically assume that the year refers to the 20th century; for example, the year 88 would be converted into 1988 (and 3 would be converted to 1903; make sure to enter 2003 explicitly into the year column to reference that year).
| Element Name | Description |
|---|---|
| General | |
| Detail of computed results reported | Specifies the level of computed results reported. If All results is selected, various graphical summaries are also computed. |
| Creates table based on | Creates the Life Table by creating a fixed number of user-defined intervals, or by applying a user-defined stepwise or interval width. |
| Correct for empty intervals | Correct intervals containing no terminations/deaths; this option determines whether intervals in which there are no deaths/terminations will be adjusted so that survival distributions can be fitted. Parameters cannot be computed for intervals where no deaths/terminations occur; by default (True) the proportion surviving in those intervals is adjusted by STATISTICA (the proportion surviving is set to .5/number exposed). Do not select this option (do not adjust) when generating a Life Table for descriptive purposes only. |
| Number Of intervals | Enter the number of intervals for the Life Table; only applicable if the table is constructed based on a user-defined number of intervals. |
| Step size | Enter the Step size to determine the intervals for the Life Table; only applicable if the table is constructed based on a user-defined step size (interval width). |
| Distribution | Select the distribution to fit to data. |
| Creates parameter estimates | Creates and reports the parameter estimates for the respective theoretical survival distribution. |
| Creates survival function | Creates and reports estimates for the survival function for each time interval, based on the chosen theoretical survival distribution. |
| Creates hazard function | Creates and reports estimates for the hazard function for each time interval, based on the chosen theoretical survival distribution. |
| Creates density function | Creates and reports estimates for the probability density function for each time interval, based on the chosen theoretical survival distribution. |