The Nonlinear Models menu allows you to fit a generalized nonlinear model.
These are models that include some nonlinear parameters, but are otherwise in
the form of generalized linear models.
Response variate
Specifies the name of the variate containing the response values.
Model Expressions
Lists of the names of the expressions that contain the calculations involving
the nonlinear parameters. You can add a new expression to the list by either
double-clicking an expression name from the Available Data list or by clicking
the New button. You can edit or remove the currently selected expression by
clicking on the Change or Remove buttons. You can change the order that the
expressions are calculated by clicking on the Reorder button.
Nonlinear Parameters
Provides a space for you to enter the names of the nonlinear parameters that
are to be estimated. The names can be separated in the list by using either a
space or ','. You can specify the initial values, upper & lower bounds and
step length for each parameter in the list by clicking on the Settings button.
Estimation includes linear parameters
Specifies whether the estimation includes linear parameters. If selected, you
can specify the maximal model, terms to be fitted and link function to be
used. Otherwise, if there are no linear parameters then you must specify
identifiers for the fitted values.
Fitted Values
If the estimation does not include linear parameters in the model you can
specify the identifiers to contain the fitted values for any set of values of
the nonlinear parameters.
Maximal Model
If the estimation includes linear parameters then you can specify the maximal
model. This allows you to specify the most complicated model that you are
likely to want to consider. It may be left blank, but this may lead to
subsequent inability to compare models because of data that are missing for
some parameters but not for others; hence Change Model is disabled in this case.
Linear Terms for Fitted Model
If the estimation includes linear parameter then you can specify the linear
terms which are to be fitted in the model.
Distribution
List of available error distributions. If you select the binomial distribution
then you must supply the binomial totals in the space provided. If you choose
the negative binomial distribution, you must also specify a fixed value for
the aggregation parameter (the parameter k in the formula for the variance in
terms of the mean: v = m + m*m/k).
Link Function
If the estimation includes linear parameters then you can select a link
function from the available list. You can choose a general power link, in
which case you need to specify the exponent; the logratio link, log(m /
(m+k)), also requires you to specify the parameter k.
Available Data
This lists data structures appropriate to the current input field. The
contents will change as you move from one field to the next. Double-click on a
name to copy it to the current input field; alternatively, you can type in the
name directly.
See Also