simstudy (version 0.7.0)

genFormula: Generate a linear formula

Description

Formulas for additive linear models can be generated with specified coefficient values and variable names.

Usage

genFormula(coefs, vars)

Value

A string that represents the desired formula

Arguments

coefs

A vector that contains the values of the coefficients. Coefficients can also be defined as character for use with double dot notation. If length(coefs) == length(vars), then no intercept is assumed. Otherwise, an intercept is assumed.

vars

A vector of strings that specify the names of the explanatory variables in the equation.

Examples

genFormula(c(.5, 2, 4), c("A", "B", "C"))
genFormula(c(.5, 2, 4), c("A", "B"))

genFormula(c(.5, "..x", 4), c("A", "B", "C"))
genFormula(c(.5, 2, "..z"), c("A", "B"))

changeX <- c(7, 10)
genFormula(c(.5, 2, changeX[1]), c("A", "B"))
genFormula(c(.5, 2, changeX[2]), c("A", "B"))
genFormula(c(.5, 2, changeX[2]), c("A", "B", "C"))

newForm <- genFormula(c(-2, 1), c("A"))

def1 <- defData(varname = "A", formula = 0, variance = 3, dist = "normal")
def1 <- defData(def1, varname = "B", formula = newForm, dist = "binary", link = "logit")

set.seed(2001)
dt <- genData(500, def1)
summary(glm(B ~ A, data = dt, family = binomial))