topic Re: why dose median() function in proc sql obtain different results? in Statistical Procedures

why dose median() function in proc sql obtain different results?

Jinlong_SUFE — Thu, 02 May 2024 19:06:49 GMT

Hi Guys,

I am trying to obtain the median value using median() function in PROC SQL as follows (SAS9.4):

/* select  clause with additional columns: Name Height*/
proc sql;
	select Name,Sex,Height,median(Height) as Med_Height,mean(Height) as Mean_Height
	from sashelp.class
	group by sex
	having sex="M";
quit;

The results are as follows:

However, when removing columns Name, Height in select clause like this:

/* select clause without additional column */
proc sql;
	select Sex, median(Height) as Med_Height, mean(Height) as Mean_Height
	from sashelp.class
	group by sex
	having sex="M";
quit;

The results are as follows:

Comparing the two tables, the mean value of Height is still 63.91 while the median of Height changes from 64.3 to 64.15 (of course the 64.15 is the right value).

Where did the first median value 64.3 come from? How did this difference (64.3 v.s. 64.15) happen? After all the mean value remains the same. I feel confused.

Can anyone explain this? Thanks a lot guys. Appreciate it.

Re: why dose median() function in proc sql obtain different results?

data_null__ — Thu, 02 May 2024 19:37:38 GMT

What SAS version. Mine is 9.4 (TS1M8) and I do not see difference.

Update: Problem Note 66896: Inconsistent results are generated with the PROC SQL Median summary function

proc sql;
	select Name,Sex,Height,median(Height) as Med_Height,mean(Height) as Mean_Height
	from sashelp.class
	group by sex
	having sex="M";
quit;

proc means data=sashelp.class n median mean;
   class sex;
   var height;
   run;
   
proc sql;
	select Sex, median(Height) as Med_Height, mean(Height) as Mean_Height
	from sashelp.class
	group by sex
	having sex="M";
quit;

Re: why dose median() function in proc sql obtain different results?

Jinlong_SUFE — Thu, 02 May 2024 20:24:59 GMT

Thx a lot. I have fixed my SAS using hot fixes.