# What does descending do in Proc logistic?

## What does descending do in Proc logistic?

If both the DESCENDING and ORDER= options are specified, PROC LOGISTIC orders the levels according to the ORDER= option and then reverses that order. This option has the same effect as the response variable option DESCENDING in the MODEL statement.

## How do I change reference levels in SAS?

Unfortunately, changing the reference in SAS is awkward for other procedures. The SAS default is to make the last category the referent, when last is determined by ordering the characters. To change this, use the order option, frequently an option to the class statement but sometimes an option to the proc statement.

**What is Param GLM in SAS?**

For PARAM=GLM, the REF= option specifies a level of the classification variable to be put at the end of the list of levels. This level thus corresponds to the reference level in the usual interpretation of the linear estimates with a singular parameterization.

### What is the reference level by default?

As you know, by default the reference level in an R model (e.g. lmer or glmer model) is alphabetically or numerically arranged.

### What is AIC in logistic regression?

The Akaike information criterion (AIC) is a mathematical method for evaluating how well a model fits the data it was generated from. In statistics, AIC is used to compare different possible models and determine which one is the best fit for the data.

**What is the reference level for a variable?**

What are reference levels. The reference level of a categorical predictor variable is often considered the “baseline” or “usual” value that is observed for the given variable. In the process of dummy coding, the variable for the reference level is left out since it would simply contain “0” for every observation.

#### What is reference level in regression?

The level of the categorical variable that is coded as zero in all of the new variables is the reference level, or the level to which all of the other levels are compared. In our example, white is the reference level. You can select any level of the categorical variable as the reference level.

#### What is the reference category in logistic regression?

A “reference group” is a group that we choose to be the reference so that all odds ratios will be a comparison to the reference group. Age (in years) is linear so now we need to use logistic regression. Logistic regression allows us to look at all three predictors (sex, weight, and age) simultaneously.

**Are GLM parametric?**

In general, we can view the point estimates from GLMs as MLEs under a particular fully parametric model for Y, or as consistent & efficient estimates resulting from assumptions on only the first and second moments of Y – i.e. a semi-parametric model.