回複：回複：親愛的SAS 互助組的朋友們，請幫幫忙

It seems the dataset was sorted by name and date.

If this is the case, take average in the first step, then delete the first date for each name and take average, and so on...

You can take out the date as a table separately if it's complicated, use it to control the delete and average process. The whole procedure can be done in PROC SQL. This is the idea you have to use if it's not in SAS but in a general database application. This is also the idea the modern program uses in Web design and interface design.