Fit Analyses |

Observations with missing values for **Y**, **X**, **Weight**, or **Freq** variables are not used. Observations with nonpositive **Weight** or **Freq** values are not used. Only the integer part of **Freq** values is used.

To view or change the response distribution and link function, click the **Method** button in the variables dialog. This displays the dialog shown in Figure 39.3.

**Figure 39.3:** Fit Method Options Dialog

You can choose the response distribution and link function of the **Y** variables. If you choose a binomial distribution, specify either

- a
**Y**variable with values 1 or 0 indicating success or failure - a
**Y**variable giving the number of successes in a certain number of trials, and a**Binomial**variable to give the corresponding number of trials

If you choose a power link function, specify the power value in the **Power** entry field.

If you select an **Offset** variable, it is treated as an **X** variable with coefficient fixed at 1.0.

You can choose the scale parameter for the response distribution. If you choose a **Constant** scale, specify the constant value in the **Constant** entry field.

With overdispersion in the model, you can specify the **Quasi-Likelihood** option to fit the generalized linear model using the quasi-likelihood functions.

If you choose a normal response distribution with a canonical link (identity for normal distributions), you can specify the **Exact Distribution** option to fit the linear model using the usual exact distributions for the test statistics.

You can specify the **Fisher's Scoring** option to use the Fisher's scoring method in the maximum-likelihood estimation for the regression parameters.

By default, SAS/INSIGHT software uses the **Normal** response distribution and **Canonical** link with the **Exact Distribution** option to perform a fit analysis for the linear model.

Copyright © 2007 by SAS Institute Inc., Cary, NC, USA. All rights reserved.