New blog format, new Stata program!

2011-09-29T10:19:00.000-07:00

Hello everyone. Since Apple is moving away from its iDisk infrastructure, iWeb will soon no longer work. Therefore, I have switched my blog to Blogspot. The layout is less snazzy, but at least it will work.

In this post, I would like to introduce my new program, gsum, for Stata. What it does is take a variable where each category is a range of a continuous variable and interpolates medians or other percentiles. It's pretty slick in that it can read the labels off your variable and use them for the range values. Personally, I think the best thing about this program is that it can create a new variable with the midpoints, which I know will make my life easier.

Here's the summary from the help file:

gsum calculates summary statistics for an ordinal variable where each category
represents a range of a conceptually continuous variable. gsum provides the weighted
N, the mean, the standard deviation, and quantiles 0.25, 0.50 (the median), and 0.75
(you can specify any set of quantiles you want). Each quantile is available as both
the midpoint of the category in which the quantile falls, or as a linear
interpolation of that quantile based on methods presented by Blalock (1979).

gsum can also produce a value table (which can also be saved) listing each category,
the range, the midpoint of that range, the number of cases, the weight of each case,
and the cumulative distribution function (CDF).

For an extra tool, gsum can also create a new variable that contains the midpoints.

gsum accepts any type of [weight] and is byable.

For example, you may have a variable age_cat where 1 represents 18-24 years of age,
2 represents 25-44 years of age, and 3 represents 45-100 years of age. You can use
gsum to calculate summary statistics such as the mean, median, and standard
deviation.

Here is how the output looks:

or if you want more detail:

to install it, simply type in Stata "ssc install gsum"

Reference:

Blalock, H.M. 1979. Social Statistics. 2nd Ed. McGraw-Hill: New York

E. C. Hedberg, Sociologist and Methodologist

New blog format, new Stata program!