topic Re: Histogram for weighted values in SAS Procedures

Histogram for weighted values

Lida — Fri, 04 Aug 2017 19:01:22 GMT

Hello,

Proc univariate does not support weight statement to build a histogram. Is there any other procedure that can be used to build a histogram for weighed values? Thank you!

Re: Histogram for weighted values

art297 — Fri, 04 Aug 2017 19:10:44 GMT

Interestingly, while it doesn't support the weight statement, it does appear to support the freq statement. e.g.,

data have;
  input score weight;
cards;
1 2
2 3
3 4
4 5
5 6
6 5
7 4
8 3
9 2
;

proc univariate data=have noprint;
   histogram score;
   freq weight;
run;

Art, CEO, AnalystFinder.com

Re: Histogram for weighted values

ballardw — Fri, 04 Aug 2017 19:18:38 GMT

Depending on numbers of levels you want you might try Proc Freq and request a FreqPlot. Heres a crude and somewhat nonsensical in real terms but generates bars using weights.

ods graphics on;

proc freq data=sashelp.class;
   weight age;
   tables weight/plots=freqplot;
run;
ods graphics off;

If you have a continuous variable with many levels you might use a custom format to create bins.

Or Proc SGPlot and a histogram plot.

proc sgplot data=sashelp.class;
   histogram height / weight = age;

run;

Re: Histogram for weighted values

Lida — Fri, 04 Aug 2017 19:37:04 GMT

that was quick and easy... 🙂 thank you very much art297.

Re: Histogram for weighted values

Rick_SAS — Mon, 07 Aug 2017 14:18:37 GMT

A weight variable is not the same as a frequency variable. A data set that has 10 observations and a frequency variable might represent 100s of observations. A data set that has 10 observations and a weight variable represents 10 data points where each observation has different influence in the analysis.

You accepted Art's answer, so should we assume that you meant "frequency-replicated observations" instead of weighted observations? If so, please consider changing the title.

Re: Histogram for weighted values

art297 — Mon, 07 Aug 2017 14:40:12 GMT

@Rick_SAS: Is there any difference with respect to producing a histogram (other than the freq variable has to be integers?)

Art, CEO, AnalystFinder.com

Re: Histogram for weighted values

Rick_SAS — Mon, 07 Aug 2017 17:26:32 GMT

That's a good question, Art. If the weights are positive integers and if you specify the bandwidth, then I think the histograms will be the same on the density scale. However, most histogram algorithms use an automated binning algorithm that chooses bins based on the number of observations, N. Since N for the frequency case isn't the same as N for the weighted case, you might get different bin widths from the automated binning algorithm. Theoretically, a frequency variable will result in smaller bin widths because there are more observations.