Hi All,   So I'm running a program to inset empty values for all variables except date values between two observations that have a gap in their date interval. For example, an observation that has 1999Q1 and the next one has 2000Q3.   Also I want to do this across bygroups in my dataset--I have a set of quarterly observations for a given individual.   I'll impute the date that goes missing after "expansion" later, but right now my main concern is getting the additional observations with the missing dates.   Thank you for the help and suggestions! ... View more