Hello,   You can find lots of info (including example programs) on the web. These are the keywords you need are: Piecewise Regression Model in SAS OR Segmented regression model in SAS OR Change point regression model in SAS   Here is a nice article (including SAS code): http://people.stat.sfu.ca/~cschwarz/Stat-650/Notes/PDFbigbook-SAS/SAS-part018.pdf Regression - hockey sticks, broken sticks, piecewise, change points   Here is an example from the SAS documentation: SAS/STAT(R) 14.1 User's Guide Example 81.1: Segmented Model https://support.sas.com/documentation/cdl/en/statug/68162/HTML/default/viewer.htm#statug_nlin_examples01.htm   Koen ... View more