# Complex Samples Ordinal Regression Model

**Specify Model Effects.**
By default, the procedure builds a main-effects model using the factors
and covariates specified in the main dialog box. Alternatively, you
can build a custom model that includes interaction effects and nested
terms.

Non-Nested Terms

For the selected factors and covariates:

**Interaction.** Creates
the highest-level interaction term for all selected variables.

**Main effects.** Creates a main-effects term for each
variable selected.

**All 2-way.** Creates all possible
two-way interactions of the selected variables.

**All
3-way.** Creates all possible three-way interactions of the selected
variables.

**All 4-way.** Creates all possible four-way
interactions of the selected variables.

**All 5-way.** Creates
all possible five-way interactions of the selected variables.

Specifying Non-Nested Build Terms

- From the
menus choose:
... or Logistic Regression or Ordinal Regression.

- Select a plan file. Optionally, select a custom joint probabilities file.
- Click Continue.
- In the main dialog box, select factors and covariates and click Model.
- Select Custom.
- Select one or more factors or covariates or a combination of factors and covariates.
- Select a method for building the terms from the Type drop-down list and add them to the model.
- Repeat the process until you have all of the terms that you want in the model.

Nested Terms

You
can build nested terms for your model in this procedure. Nested terms
are useful for modeling the effect of a factor or covariate whose
values do not interact with the levels of another factor. For example,
a grocery store chain may follow the spending habits of its customers
at several store locations. Since each customer frequents only one
of these locations, the *Customer *effect can be said to be **nested
within **the *Store location *effect.

Additionally, you can include interaction effects, such as polynomial terms involving the same covariate, or add multiple levels of nesting to the nested term.

**Limitations.** Nested terms have the following
restrictions:

- All factors within an interaction must be unique. Thus, if
*A*is a factor, then specifying*A*A*is invalid. - All factors within a nested effect must be unique. Thus, if
*A*is a factor, then specifying*A(A)*is invalid. - No effect can be nested within a covariate. Thus, if
*A*is a factor and*X*is a covariate, then specifying*A(X)*is invalid.

Specifying Nested Build Terms

- From the
menus choose:
... or Logistic Regression or Ordinal Regression.

- Select a plan file. Optionally, select a custom joint probabilities file.
- Click Continue.
- In the main dialog box, select factors and covariates and click Model.
- Select Custom.
- Select a factor or covariate that is nested within another factor, and then click the move button.
- Click Nesting.
- Select the factor within which the previous factor or covariate is nested, and then click the move button.
- Click Add to Model.
- Optionally, you can include interaction effects or add multiple levels of nesting to the nested term.