The Define Summary Intervals dialog, which is accessed from the Parameters tab in a Survival session, allows you to quickly create a custom set of survival intervals for use in cumulative summary tables.

This dialog presents four choices that you can use to automatically create a set of intervals with a certain pattern. Select one of these options to change the value of the Intervals field as described. If the **Include 0th Interval** check box in the Intervals section of the Parameters tab is marked, each of these options will also include interval 0.

**All Intervals**– Your set will contain every interval, from "1" through the total number of intervals.**Annual**– Your set will contain each interval that represents the end of a year, plus the final interval if it is not already included. For example, if you use 21 intervals of three months each, this option will set your Survival Matrix intervals to "4,8,12,16,20,21" -- the first five coming at the end of years one through five, and the sixth at five years and three months. This option will be unavailable if your number of months per interval is not a factor of 12 (i.e., 1, 2, 3, 4, 6, or 12), since intervals that precisely mark the end of a year cannot always be chosen in that case.**Semi-annual**– Your set will contain each interval that marks the end of six months, plus the final interval if it is not already included. For example, if you use 19 intervals of one month each, this option will set your Survival Matrix intervals to "6,12,18,19". Similarly to the**Annual**option, this option will be unavailable if your number of months per interval is not a factor of 6 (i.e., 1, 2, 3, or 6).**Every**– Your set will contain each interval that marks the end of a number of months of your choosing, which must be a multiple of your number of months per interval. The default is the same as your number of months per interval, which is equivalent to the*N*months**All Interval**s option.

Alternatively, here or on the Parameters tab, you can define your own set of intervals by typing in the Intervals field. The interval numbers must be in order from lowest to highest, and separated by commas. The number of intervals and number of months per interval, which you specified in the Intervals section of the Parameters tab, are listed below the Intervals field on this dialog for reference. If you enter an interval number higher than the total number of intervals, SEER*Stat will issue an error message when you try to execute the session.

If you decide not to define new intervals, click **Cancel** to return to the Parameters tab. The intervals that were previously listed will not be changed.

To accept the new set of intervals, click **OK**. You will return to the Parameters tab, and the **Interval** field will be automatically filled with your newly defined intervals.