## how to get p-value from pairwise comparisons

Frequent Contributor
Posts: 84

# how to get p-value from pairwise comparisons

Hi All,

I am trying to do pairwise comparisons to see the difference of means within each two groups (I have four groups totally). But in the SAS output below, the last column shows which group comparison is significant or not. But I want to get the p-value of the last column, not just star signs. Any idea?

Here is my output Table:

 Comparisons significant at the 0.05 level are indicated by ***. groupComparison DifferenceBetweenMeans Simultaneous 95% Confidence Limits (1) Toddler - (2) Young 8.862 0.592 17.131 *** (1) Toddler - (3) Child 16.756 8.674 24.838 *** (1) Toddler - (4) Teen 20.183 11.744 28.621 *** (2) Young   - (1) Toddler -8.862 -17.131 -0.592 *** (2) Young   - (3) Child 7.894 0.574 15.214 *** (2) Young   - (4) Teen 11.321 3.608 19.033 *** (3) Child   - (1) Toddler -16.756 -24.838 -8.674 *** (3) Child   - (2) Young -7.894 -15.214 -0.574 *** (3) Child   - (4) Teen 3.427 -4.084 10.938 (4) Teen    - (1) Toddler -20.183 -28.621 -11.744 *** (4) Teen    - (2) Young -11.321 -19.033 -3.608 *** (4) Teen    - (3) Child -3.427 -10.938 4.084

Here is my code:

proc anova data=combine;
class group;
model variable = group;
means group / BON;
run;

proc glm data=combine;
class group;
model variable = group;
means group / bon;
run;

Thanks,

C

SAS Super FREQ
Posts: 3,831

## Re: how to get p-value from pairwise comparisons

use

Complete example:

``````
proc glm data=sashelp.cars;
class type;
model mpg_city = type;
run;``````

The doc shows many ways to adjust the p-values for multiplicity.  I like Bonferonni and SIMULATE.

Frequent Contributor
Posts: 84

## Re: how to get p-value from pairwise comparisons

Hi Rick,

Yes, I got this way before, but in this way, SAS outputs P-value table in as a matrix (as shown below). Then I have to write a long code to reorganize the p-values along with group comparison so they can display as one column (as the last column in the table shown in my question). I think that's a complex way....

 Least Squares Means for effect groupPr > |t| for H0: LSMean(i)=LSMean(j)Dependent Variable: Variable i/j 1 2 3 4 1 0.0047 <.0001 <.0001 2 0.0047 0.0045 0.0001 3 <.0001 0.0045 0.2270 4 <.0001 0.0001 0.2270

Any way to show the p_values in the last column instead of star signs like in the below table directly?

 Comparisons significant at the 0.05 level are indicated by ***. groupComparison DifferenceBetweenMeans 95% Confidence Limits (1) Toddler - (2) Young 8.862 2.732 14.992 *** (1) Toddler - (3) Child 16.756 10.764 22.747 *** (1) Toddler - (4) Teen 20.183 13.927 26.438 *** (2) Young   - (1) Toddler -8.862 -14.992 -2.732 *** (2) Young   - (3) Child 7.894 2.467 13.320 *** (2) Young   - (4) Teen 11.321 5.604 17.038 *** (3) Child   - (1) Toddler -16.756 -22.747 -10.764 *** (3) Child   - (2) Young -7.894 -13.320 -2.467 *** (3) Child   - (4) Teen 3.427 -2.141 8.995 (4) Teen    - (1) Toddler -20.183 -26.438 -13.927 *** (4) Teen    - (2) Young -11.321 -17.038 -5.604 *** (4) Teen    - (3) Child -3.427 -8.995 2.141

Thanks,

C

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