st: rsd vs. summarize

["Olga Gorbachev Melloni" <olga_gorbachev@hotmail.com>]

Hello,

I have a potentially silly question, so I apologize in advance.

I am trying to compute standard deviation of income for each person over 5 
year time period (specifically, it is a 5 year rolling standard deviation 
for each person in the panel).

When I do this by collecting standard deviations reported by summary command 
through 'rolling', they are slightly different but sometimes even move in 
different directions, when compared to standard deviations computed using 
rsd (row standard deviation -- used after creating lags of income data for 
each person) -- and it is not due to missing observations, I checked that.

Do you have any idea why there is a difference and if so what is it?

Thank you in advance,
Olga


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