Graph weighted averages in Stata

Question

I'm doing an analysis of the Current Population Survey. I have a wage variable (wage), a time-series variable (qtr), and an observational weight (pworwgt). Each quarter has thousands of observations.

I can easily make a table showing the weighted average wage in each quarter:

table qtr [iw=pworwgt], contents(mean wage)

What I want to do, however, is graph this easily within Stata. I tried to use egen to make a variable containing the mean by qtr, but egen mean() does not allow for weights.

It may be easy just to use egen's total() function to get the numerator and denominator of a weighted average, and then divide. There is a user-written egen function for this purpose, but doing it from first principles should be easy and instructive. Or even easier is to use collapse to get a reduced dataset of averages. — Nick Cox

dimitriy dimitriy · Accepted Answer · 2015-02-12T00:32:30

One of the many ways this can be done is with a regression followed by two margins* commands:

webuse hanley
table rating [iw=pop], contents(mean disease)
reg disease i.rating [iw=pop]
margins rating
marginsplot, noci

This has the advantage of not altering your data in any way.

Graph weighted averages in Stata

1 Answers