[ferret_users] question on yearly average

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Subject: [ferret_users] question on yearly average

From: Paul Goddard <goddarpb@xxxxxxxxx>

Date: Wed, 14 Aug 2013 09:01:05 -0700

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Hi,

I have a basic question but it is made me wonder for quite some time. Let's say I have 20 years of monthly data, Jan 1993 -Dec 2012, and I want to list out the yearly average of those months. I usually compute,

list = var[L=1:240:12@AVE]

The output is 20 data points, however, the values are not the same as if I extract the 1:240 data points into excel and calculate the average for each year "by hand."

Why the discrepancy? and what should I do if I want to calculate yearly means.

Thanks in advance,

Paul