Maarten L. Buis

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proprcspline: module for restricted cubic spline smoothing of proportions.

Author: Maarten L. Buis

Description

proprcspline computes a restricted cubic spline smooth of proportions of observations in each category of a dependent/response/explained variable given an independent/predictor/explanatory variable, and graphs these smoothed proportions as a stacked area plot.

This package can be installed by typing in Stata: ssc install proprcspline

Supporting material

• summary on ssc.
• helpfile
• Announcement of proprcspline on statalist.
• Certification script for version 1.2.3

Examples

Illustrating the basic syntax and the resulting graph (I used the lean1 scheme):

. sysuse nlsw88, clear
(NLSW, 1988 extract)

.    
. gen marst = cond(never_married, 1,              ///
>             cond(married, 2, 3))                ///
>             if !missing(married, never_married)

. label define marst 1 "never married"            ///
>                    2 "married"                  ///
>                    3 "divorced/widowed"

. label value marst marst

. 
. proprcspline marst grade, xlab(0(5)15) 

[do-file]

Illustrating the by() option:

. sysuse nlsw88, clear
(NLSW, 1988 extract)

. 
. gen marst = cond(never_married, 1,              ///
>             cond(married, 2, 3))                ///
>             if !missing(married, never_married)

. label define marst 1 "never married"            ///
>                    2 "married"                  ///
>                    3 "divorced/widowed"

. label value marst marst

. 
. gen black = race == 2 if race < .

. label define black 1 "black"                    ///
>                    0 "non-black"

. label value black black    

. 
. proprcspline marst grade, xlab(0(5)15)          ///
>                           by(black, note(""))

[do-file]