How do I convert monthly data to quarterly using as the value of the quarter the value of the 1st month of each quarter?

I have a dataset of monthly data on CPI and I want to convert it to quarterly. I tried to use timetable but it didn't work I think.

Answer 1

[Cris LaPierre]

Not knowing anything about the format of your data, I would suggest using groupsummary. This will allow you to determine how to summarize the monthly data to quarterly data (average, sum, etc). If your data is already in a table or timetable, and your date info is already a datetime, you can use the 'quarter' groupbin.

Perhaps this example can help get you started. The code might be something like this

qtrCPI = groupsummary(mnCPI,"Timestamp","quarter","mean")

Answer 2

[Eric Sofen]

Another timetable option is to use retime with the 'firstvalue' aggregation method.