On Thu, Jan 17, 2013 at 8:13 PM, Nahla Betelmal wrote:
>> I performed qnorm and it seems that there is an outlier observation, so I will either winsorize or trim the data and run both tests again.
Before you do that you need to try to figure out why this number is an
outlier. Just type in Stata -list if DA_T_1 > 200 & DA_T_1 < .- and
Stata will give you the values on all variables for your outlier. This
often helps in determining why this observation is special. Also look
at the value on DA_T_1 itself: Did someone forget to type a decimal
point when typing in the data? Is it a (mistyped) numeric code for a
missing value? Once you know that you can make an informed decision,
rather than using a "blind" technique like winsorize.
-- Maarten
---------------------------------
Maarten L. Buis
WZB
Reichpietschufer 50
10785 Berlin
Germany
http://www.maartenbuis.nl
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