The trend variable defines the year ranges for which SEER*Stat computes the trends. Groupings that do not contain at least two consecutive years, or that contain non-contiguous years, will be ignored in trend calculations. Percent Change (PC) calculations with two-year average end points and Annual Percent Change (APC) calculations require at least three consecutive years. For each correctly defined grouping, SEER*Stat calculates the PC and the APC, and compares the APC to 0 for significance.

SEER*Stat also tests for significance in comparisons between APCs and a base APC. The first grouping listed in the dictionary's definition of the trend variable serves as the base APC. If a grouping has any years overlapping the base year grouping, this significance test cannot be performed.

If you wish to change the year groupings for your analysis, create a user-defined variable based on the standard trend variable for your database. For the SEER Limited-Use databases, the "Year of diagnosis" variable is the default trend variable.

The trend variable is automatically added as the innermost row variable of your results matrix, and therefore should not be added on the Table tab.