This dialog is used to specify a linear model to be fit by the `lm`

function.

The left model-formula box specifies the response variable to be used in the model; it
may be a variable name or an expression evaluating to the response variable, such as
`log(income)`

.

The right model-formula box specifies the right-hand (i.e., predictor) side of the model.
See `lm`

for details.

You can type directly in the model formula boxes. Alternatively, double-clicking the left mouse
button on a variable in the variable-list transfers it to the left-hand side of the model (if
it is empty or selected) or to the right-hand side. You can also enter operators and parentheses using the buttons
above the formula. If you select several variables in the variable-list box, clicking on the
`+`

, `*`

, or `:`

button will enter them into the model formula.

Specifying a subset expression allows you to fit the model to a subset of observations
in the active data set. For example, assuming that `gender`

is a variable in the
active data set, entering `gender == "Male"`

would restrict the model to males.

If the active model is a linear model and the active data set has not changed, then the initial values of the left-hand-side, right-hand-side, and subset fields are retained from the previous model.

John Fox jfox@mcmaster.ca

Questions? Problems? Suggestions? Tweet to @rdrrHQ or email at ian@mutexlabs.com.

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