Hello,
Hello,
I have those parameters from a multinomial logit regression that explains Education (L/M/H) by language (Dominant/Other Europe/Non-European).
proc logistic data=edu.educationClean;
class Language(ref='Dom') /param=ref;
model edu3(ref='H')= Language /link=glogit rsquare;
weight pond / norm;
where model=1;
run;
Analysis of Maximum Likelihood Estimates | |||||||
Parameter | edu3 | DF | Estimate | Standard | Wald | Pr > ChiSq | |
Error | Chi-Square | ||||||
Intercept | L | 1 | -0.7505 | 0.0134 | 3131.38 | <.0001 | |
Intercept | M | 1 | 0.159 | 0.0103 | 236.585 | <.0001 | |
Language | Europe | L | 1 | -0.0533 | 0.0841 | 0.4021 | 0.526 |
Language | Europe | M | 1 | -0.2527 | 0.0677 | 13.9402 | 0.0002 |
Language | Non-Europe | L | 1 | 1.5045 | 0.0729 | 426.15 | <.0001 |
Language | Non-Europe | M | 1 | 0.2267 | 0.0773 | 8.6057 | 0.0034 |
The parameter (-0.0533) thus compares L to H for Other Euoprean compared to Dominant (reference category). Now I want to know what is the parameter for L compared to all others (M+H), so I was going to do -0.0533-(-0.2527)=0.1994.
1-Is this correct?
2-If so, why, when I perform a binominal logit regression (L vs Other), I get these parameters. In my mind, it should give the same.
proc logistic data=edu.educationClean;
class Language(ref='Dom') /param=ref;
model LOW(ref='0')= Language /link=glogit rsquare;
weight pond / norm;
where model=1;
run;
Analysis of Maximum Likelihood Estimates | |||||||
Parameter | LOW | DF | Estimate | Standard | Wald | Pr > ChiSq | |
Error | Chi-Square | ||||||
Intercept | 1 | 1 | -1.5263 | 0.0122 | 15662.1 | <.0001 | |
Language | Europe | 1 | 1 | 0.0751 | 0.0776 | 0.9348 | 0.3336 |
Language | Non-Europe | 1 | 1 | 1.3759 | 0.0566 | 591.027 | <.0001 |
"L compared to all others (M+H)" defines a cumulative logit. The relationship between the parameters of the nominal and ordinal models is a much more complex nonlinear function. But, to get the parameters on a model using cumulative logits like you want, all you need to do is change your model from a generalized logit model to an ordinal logit model that allows unequal slopes for the two cumulative logits, like so:
proc logistic data=edu.educationClean;
class Language(ref='Dom') /param=ref;
model edu3(ref='H')= Language / unequalslopes;
weight pond / norm;
where model=1;
run;
"L compared to all others (M+H)" defines a cumulative logit. The relationship between the parameters of the nominal and ordinal models is a much more complex nonlinear function. But, to get the parameters on a model using cumulative logits like you want, all you need to do is change your model from a generalized logit model to an ordinal logit model that allows unequal slopes for the two cumulative logits, like so:
proc logistic data=edu.educationClean;
class Language(ref='Dom') /param=ref;
model edu3(ref='H')= Language / unequalslopes;
weight pond / norm;
where model=1;
run;
Are you ready for the spotlight? We're accepting content ideas for SAS Innovate 2025 to be held May 6-9 in Orlando, FL. The call is open until September 25. Read more here about why you should contribute and what is in it for you!
ANOVA, or Analysis Of Variance, is used to compare the averages or means of two or more populations to better understand how they differ. Watch this tutorial for more.
Find more tutorials on the SAS Users YouTube channel.