I'm having difficulty with some data that is not on the same timeline. One series is monthly and the other is quarterly. My original thought was to convert the quarterly to monthly via estimation, but that might be overly complicated. It might be simpler to convert the monthly data to quarterly data by deleting the non-congruous months.

So I need a macro that will allow me to delete two out of every three months. For instance, if I only need January, April, July, and October data, I would need to delete the other months.

Here's what my data looks like:

Jan-1949 1.3%
Feb-1949 1.3%
Mar-1949 1.7%
Apr-1949 0.4%
May-1949 -0.4%
Jun-1949 -0.8%
Jul-1949 -2.9%
Aug-1949 -2.9%
Sep-1949 -2.4%
Oct-1949 -2.9%
Nov-1949 -1.7%
Dec-1949 -2.1%
Jan-1950 -2.1%
Feb-1950 -1.3%
Mar-1950 -0.8%
Apr-1950 -1.3%
May-1950 -0.4%
Jun-1950 -0.4%
Jul-1950 1.7%
Aug-1950 2.1%
Sep-1950 2.1%
Oct-1950 3.8%
Nov-1950 3.8%
Dec-1950 5.9%
Here's what I need it to look like after the deletions:

Jan-1949 1.3%
Apr-1949 0.4%
Jul-1949 -2.9%
Oct-1949 -2.9%
Jan-1950 -2.1%
Apr-1950 -1.3%
Jul-1950 1.7%
Oct-1950 3.8%
How would I design a macro to do this?