Data processing problem

[deleted_user]

Dear forum members,

I have a data set with three columns. One is series of times. The second is a column which is mainly missing values. The third is also numeric.

What I need to do is, for every non-missing value in the second column, create a data set with the mean value of the third column for every observation before the time of the non-missing value that is within three hours of that observation.

Grateful for any suggestions,

Paul J

[DBailey]

Are the times unique in the dataset?

[deleted_user]

Dear DBailey,

The times are unique, that is no two rows should have exactly the same time,

Thanks

Paul