The average age of Whites in the sample, conditional on being older than 25, is 44 years old. To obtain this answer we again need to use the means command to produce the average value of the age variable, in addition to a qualifier, which will restrict the calculation to Whites that are over the age of 25. To do this we type the following in Stata:
means age if race == 4 & (age > 25 & age~=.)
The above command produces the following table:
Variable | Type Obs Mean [95% Conf. Interval]
-------------+----------------------------------------------------------
age | Arithmetic 236 44.97458 43.28791 46.66125
| Geometric 236 43.20502 41.67549 44.79069
| Harmonic 236 41.5883 40.19294 43.08403
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From the table we can see that the average age of Whites over the age of 25 in the sample is roughly 44 years old.