- Thread starter statanx
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Another day, I was reading a paper book. Then the urge to hit the control+F keys emerged frequently!

Computer (and technology) have slaved us all. (and the bots living in the cyberspace might as well)

But can't we trick SPSS by putting the covariates in the model and running the post hocs? I mean once we can run the MANCOVA as is, and then put those covariates into the model and run the Bonferroni. I wonder how that would affect the reliability of the result. I know it is not correct, but it is the only choice after pencil/paper, and looking for another good statistical package.

I am currently testing this on other software.

Well, no, it's not, victor....What you want to do is go to options and bring the grouping variable over into "Display Means for:" and then click the box for "Compare Main effects" and your options are LSD, Bonferroni, and Sidak.

So why did you mention the deactivation of the post hocs in the first place? And why SPSS developers have done this incosnsitent path to first disallow you to do something, and then provide you with the disallowed thing in a hidden place?!

I see its subcommand changes to the below code. meaning that SPSS considers it something different from a simple post hoc test.

Code:

`/EMMEANS=TABLES(Var1) WITH(Var2=MEAN) COMPARE ADJ(LSD)`

That was one good hint Dragan. Thanks

So why did you mention the deactivation of the post hocs in the first place? And why SPSS developers have done this incosnsitent path to first disallow you to do something, and then provide you with the disallowed thing in a hidden place?!

I see its subcommand changes to the below code. meaning that SPSS considers it something different from a simple post hoc test.

So why did you mention the deactivation of the post hocs in the first place? And why SPSS developers have done this incosnsitent path to first disallow you to do something, and then provide you with the disallowed thing in a hidden place?!

I see its subcommand changes to the below code. meaning that SPSS considers it something different from a simple post hoc test.

Briefly, in the denominator of the t-statistic for comparing adjusted means for ANCOVA, the standard error is;

Sqrt [MSw [ 1/ni + 1/nj + [ (Xbar_i - Xbar_j)^2 / SSres(X) ] ]

where MSw is the adjusted mean squares within from the overall analysis and X is the covariate.

I mentioned it because a lot of people don't understand that the usual post-hoc ANOVA tests e.g. Tukey, etc. are not appropriate for ANCOVA because the standard error is not computed correctly.

Briefly, in the denominator of the t-statistic for comparing adjusted means for ANCOVA, the standard error is;

Sqrt [MSw [ 1/ni + 1/nj + [ (Xbar_i - Xbar_j)^2 / SSres(**X**) ] ]

where MSw is the adjusted mean squares within from the overall analysis and X is the**covariate**.

Briefly, in the denominator of the t-statistic for comparing adjusted means for ANCOVA, the standard error is;

Sqrt [MSw [ 1/ni + 1/nj + [ (Xbar_i - Xbar_j)^2 / SSres(

where MSw is the adjusted mean squares within from the overall analysis and X is the

I prefer it (LSD) because the Bonferroni adjustment is too conservative. Note that the omnibus F-test should be significant to use the LSD approach.

I think I need to go through all these post hoc procedures in detail.

Can you please provide me with link (if you have) having the step wise procedure for ANCOVA/MANCOVA and the post hoc procedures?

Now hit the button labeled "Options". Drag or insert your desired variables into a box labeled "Display means for".

Then check the option "Compare main effects" below that box.

Then from the drop-down menu below that box and that checked option, select one of the options "Bonferroni, LSD, or Sidak".

Here is the step by step instruction to do MANOVA and MANCOVA:

http://www.ucdenver.edu/academics/colleges/nursing/Documents/PDF/MANOVAHowTo.pdf

Note that ANCOVA is similar. But the dialog box opens from the "Univariate" option (instead of Multivariate).