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FestusAdejoro
Obsidian | Level 7

How do I do slice test for effects when interaction is significant in 2 X 2 factorial

 [ New ] 
 

 Dear SIr/Ma,

I had tried to analyse a 2 X2 factor experiment with PROC GLM. I reported the P-values for A, B and AB interaction.

My SAS syntax was of this fashion:

proc univariate plot normal;
title 'Trial4Digest';
var v1;
run;
Proc GLM Order = Data;
Class A B;
Model v1 = block A B A*B;
LSmeans A*B/TDIFF PDIFF P STDERR Adjust=tukey;
Run;
Quit;

 

1. Where interaction was NOT SIGNIFICANT, I had used the simple effect of each factor to compare my means and report in result and discussion.

2. Where interaction was SIGNIFICANT and either FActor A or B is Sig, or FActor A or B is NOT SIGNIFICANT, i had used tukey test to assign "abcd" to the means for comparisons.

 

A1

A2

 

P-values

3Parameter

B-

B+

B-

B+

SEM

A

B

A*B

Ac

58.4

51.5

54.2

55.7

0.71

0.86

0.02

˂0.01

Pro

20.5b

23.3a

22.5a

23.2a

0.39

0.07

<0.01

0.05

Bu

15.5

18.8

17.5

15.8

0.37

0.40

0.19

˂0.01

Bra

3.66

3.96

3.80

3.30

0.10

0.19

0.54

0.04

Val

1.95b

2.39a

1.98b

2.00b

0.06

0.02

<0.01

0.01

Ap

3.03a

2.25b

2.46b

2.43b

0.09

0.175

0.01

0.01

 

This is the response of the reviewer:

" The use of Tukey's test to separate means is incorrect. Actually, it is not acceptable to use two statistical tests to show a difference between treatments (treatments and interaction effects and mean separation). I greatly discourage the authors from using mean separation when the effect of treatment (factor A, factor B and interaction) is displayed in the tables. A slice test can be used when the interaction is observed. Therefore Tables and text (where appropriate) should be corrected".

 

I do not have a clue on the way forward on using this slice test and how to interpret the subsequent result. Any help to modify my syntax and report correctly will be appreciated. 

1 ACCEPTED SOLUTION

Accepted Solutions
1 REPLY 1
PaigeMiller
Diamond | Level 26

There is a SLICE= option in the LSMEANS statement, that sounds like what you want.

 

https://documentation.sas.com/?docsetId=statug&docsetTarget=statug_glm_syntax10.htm&docsetVersion=15...

--
Paige Miller

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