# Re: st: Command -contrast- after -anova

 From David Airey To statalist@hsphsun2.harvard.edu Subject Re: st: Command -contrast- after -anova Date Tue, 9 Dec 2008 09:18:21 -0600

```see -anovacontrast- from ATS UCLA by Phil Ender

-Dave

On Dec 9, 2008, at 8:06 AM, Herve STOLOWY wrote:

```
```Dear Statalisters:

```
I have some difficulties in using the -constrast- command (downloadable from ssc) after -anova-.
```
Here is my -anova- command line with the output.

```
anova return info risk info*risk if round>7 & round<26 & offer==1 & win==1, detail
```
Factor        Value          Value          Value          Value
```
------------------------------------------------------------------------
``` info          1 0            2 1

risk          1 0            2 1

```
Number of obs = 2309 R-squared = 0.0401 Root MSE = .026537 Adj R-squared = 0.0389
```
```
Source | Partial SS df MS F Prob > F ----------- +---------------------------------------------------- Model | .067894615 3 .022631538 32.14 0.0000
```                        |
```
info | .007341846 1 .007341846 10.43 0.0013 risk | .045207121 1 .045207121 64.20 0.0000 info*risk | .010246209 1 .010246209 14.55 0.0001
```                        |
Residual |  1.62318282  2305  .000704201
```
----------- +----------------------------------------------------
```                  Total |  1.69107744  2308  .000732703

In the -contrast- command, I use the following syntax:

```
contrast return info risk, coeffs(1 1), if round>7 & round<26 & offer==1 & win==1
```
and it does not work.

```
I am almost sure that the figures after coeffs are wrong. To be honest, I do not understand very well the help file of -contrast-. (I tried the examples given in this file, based on auto.dta, but it returns an error message).
```
Does someone have some practice with -contrast-?

```
(I read the Stata manual and the differents threads in the Statalist. It seems that the -contrast- command should avoid using the command -test- with matrices after anova).
```
Best regards

Herve

***********************************************************
Professeur/Professor
President of the French Accounting Association (AFC)
HEC Paris
```
Departement Comptabilite Controle de gestion / Dept of Accounting and Management Control
```1, rue de la Liberation
78351 - Jouy-en-Josas
France
Tel: +33 1 39 67 94 42 - Fax: +33 1 39 67 70 86
mail: stolowy at hec dot fr
web: http://www.hec.fr/stolowy

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```
```
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```