I need to calculate the number of days between multiple records where the member ID is the same. For further clarification I'm trying to report on patients who visit an ER 3 or more times within a 30 day period. However there is a catch, a patient may visit ER once, let's say on 01/01/03 then not return until 03/01/03 and again on 03/03/03 and again on 03/05/03 and again on 03/15/03. Which if this is the scenario I do not want to count the ER visit on 01/01/03, just the following 4 visits. Any thoughts and ideas would be greatly appreciated!!