topic Re: PROC UNIVARIATE output explanation in SAS Procedures

PROC UNIVARIATE output explanation

Tsegazaab — Sun, 04 Sep 2016 20:48:16 GMT

Hello;

I coded a proc univariate to analyze the variable FEV for smokers and non-smokers. Let me write the code here and the output as well.

PROC MEANS DATA=pulfun;
CLASS smoke;
VAR fev;
RUN;


PROC SORT DATA=pulfun;
BY smoke;
RUN;

PROC UNIVARIATE DATA=pulfun PLOT;
By smoke;
VAR fev;

And, I got the output attached as PDF file. My question is:

"Based on the output of PROC UNIVARIATE, describe the differences and similarities in the shapes of the FEV distributions for smokers and non-smokers. Specifically identify the features of the output that you used."

Help me please. Thank you!

Re: PROC UNIVARIATE output explanation

Reeza — Sun, 04 Sep 2016 21:04:10 GMT

It's easier to make a comparison if they're overlayed in some manner.

Try the histogram statement.

Re: PROC UNIVARIATE output explanation

Tsegazaab — Sun, 04 Sep 2016 21:15:34 GMT

So, could you answer my question please? I am not clear with that concept. I am waiting.

Thank you!

Re: PROC UNIVARIATE output explanation

Reeza — Sun, 04 Sep 2016 21:44:32 GMT

Distributions have specific features that are used for comparison:

measure of center such as median/mean

Tails

Outliers

You can compare the distributions using the graphs and/or the box plot. I find a box plot easier to write up a comparison.

So how do smokers compare for the median and mean for the FEV variable? Are the tails longer in one than the other? In a specific direction? What about outliers between the two?

Khan Academy has a full chapter on this topic (Comparing features of a distribution). They do a better job of explaining this than I would.

https://www.khanacademy.org/math/statistics-probability/displaying-describing-data/comparing-features-distributions/v/comparing-dot-plots-histograms-and-box-plots

This is clearly homework so this as much of an answer I'm willing to provide (my personal rule). Others may (or may not) choose to provide more assistance. Good Luck.

Re: PROC UNIVARIATE output explanation

Rick_SAS — Mon, 05 Sep 2016 14:58:04 GMT

Look at the comparative histograms. Also use

ods graphics on;

and get rid of the PLOT option.