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Posted 09-25-2018 12:38 PM
(2973 views)

Hi, this is my first post on SAS. I have a split plot design in 5 factors. Factors A, B, and C have 3 levels and are hard to change factors applied to the main plots. Each main plot contains one combination of A,B,C (so 27 main plots in the 3^3 main plot factorial). The sub plot receives a 3^2 factorial in easy to change factors (D, E). Every example I find only discusses how to write the SAS program for Factors A and B. I replicate the entire design twice.

I cant find anything on how to adjust the below SAS code to handle 3 factors in the main plot and two factors in the subplots.

Simple Split plot in 2 factors:

proc mixed; class A B Block; model Y = A B A*B; random Block A*Block; run;

Can someone help or point me in the right direction? much appreciated.

8 REPLIES 8

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If I understand your design you can think of it this way.

```
data split;
do block=1,2;
whole=0;
do a=1 to 3;
do b=1 to 3;
do c=1 to 3;
whole+1;
sub=0;
do d=1 to 3;
do e=1 to 3;
sub+1;
y = rannor(13456);
output;
end;
end;
end;
end;
end;
end;
run;
proc print;
run;
proc mixed data=split method=type1;
class block whole sub;
model y = whole sub whole*sub;
random block whole*block;
run;
proc mixed data=split method=type1;
class block a b c d e;
model y = a|b|c|d|e;
random block a*b*c*block;
run;
```

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This first one is the analysis in terms of a single treatment whole plot and subplot. 27 whole plots treatments and 9 subplots.

This is a check for the second MIXED where we partition the whole plots (df=26) into the factorial effects a|b|c. Same for SUB df=8 and SUB*WHOLE df=208 are partitioned into all the many effects of a|b|c|d|e that remain.

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Output from second PROC MIXED.

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@shaz71 wrote:

Looks like there are no complete blocks. Looks like subplots are blocked (REP 1/2) within whole plots. I don't think the model with BLOCKS is correct for this design.

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