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lc7033907
Obsidian | Level 7

Hello all,

 

I want to use sashelp.class as an example to get mean and SE (standard error) values of height by proc mixed and I like to save these values in a dataset.  I found all the SE values are the exactly the same. This is my first time to touch proc mixed, so I really get confused. Anyone can give me some  explanation? Thanks.

 

proc mixed data=sashelp.class(where=(Age in (14,15)));
  class Sex  Age;
  model Height = Sex  Age;
    lsmeans Sex  Age;
run;

Here is output:mixed_output.PNG

6 REPLIES 6
PaigeMiller
Diamond | Level 26

I think that's what is supposed to happen with the SE when you estimate some type of linear model for the two-way ANOVA case, and there are equal number of observations in each cell. 

--
Paige Miller
lc7033907
Obsidian | Level 7

Hi @PaigeMiller , anyway to correct it, because I guess those numbers should not be equal. Thanks.

PaigeMiller
Diamond | Level 26

@lc7033907 wrote:

Hi @PaigeMiller , anyway to correct it, because I guess those numbers should not be equal. Thanks.


You are incorrect. The SE numbers should be equal in this example.

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Paige Miller
lc7033907
Obsidian | Level 7

@PaigeMiller Thank you. Now let me modify my real problem  and I hope to get some hints. The following is data that I have

data have;
input subjid $2.   Avisitc $3-10 trt $ CHG;
datalines;
1 week 12 A 3.7
1 week 16 A 4.8
2 week 12 B -2
2 week 16 B -2.2
3 week 12 A -3
3 week 16 A -2.5
4 week 12 B 2.8
4 week 16 B 3.0
5 week 12 A 7.0
5 week 16 A 7.1
6 week 12 B 6.4
6 week 16 B 6.8
7 week 12 A -5
7 week 16 A -5.4
8 week 12 B 10
8 week 16 B 11
9 week 12 B -6.4
9 week 16 B -7.1
10 week 12 A 6.3
10 week 16 A 6.9
;

I want to get a report in the following:

report_want.PNG

 Now I have trouble on the last column, because I never use proc mixed before. Any hints are appreciated. Thanks.

PaigeMiller
Diamond | Level 26

You can get most of this from PROC MIXED

 

ods select lsmeans;
proc mixed data=have;
    class avisitc trt;
    model chg = avisitc*trt;
    lsmeans avisitc*trt;
run;
quit;

If it has to be displayed EXACTLY as shown, then that is a job for other PROCs, and I would recommend you start another thread to discuss how to display results exactly in the desired report form.

 

 

--
Paige Miller
lc7033907
Obsidian | Level 7

Thank you so much @PaigeMiller . Your code is exactly the same as what I did on my own. Since I got the same values on SE, I thought I was wrong. Thank you once again.