Programming the statistical procedures from SAS

2 way random effects ANOVA

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Regular Contributor
Posts: 204

2 way random effects ANOVA

Hi everyone.

May I please ask what this " Convergence criteria met but final
hessian is not positive definite" outputed by proc mixed means?

my code is
proc mixed data=temp;
class Subject factory;
model log_exp = / solution;
random int / subject=Subject solution;
random int / subject=factory solution;
random int / subject=factory *Subject solution;
run;

Many thanks in advance.
Contributor
Posts: 20

Re: 2 way random effects ANOVA

Usually, this means the calculations came up with a negative value for one of the variance components. Take a look at the Covariance Parameter Estimates, and you should see one set to 0. You may need to adjust your model accordingly to avoid this situation.
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