This help file describes the distributions used for data creation in simstudy.

## Arguments

formula Desired mean as a Number or an R expression for mean as a String. Variables defined via defData() and variables within the parent environment (prefixed with ..) can be used within the formula. Functions from the parent environment can be used without a prefix. Number. Default is 0. String identifying the link function to be used. Default is identity.

## Details

For details about the statistical distributions please see stats::distributions, any non-statistical distributions will be explained below. Required variables and expected pattern for each distribution can be found in this table:

 name formula format variance link beta mean String or Number dispersion value identity or logit binary probability for 1 String or Number NA identity or logit binomial probability of success String or Number number of trials identity or logit categorical probabilities p_1;p_2;..;p_n NA NA exponential mean (lambda) String or Number NA identity or log gamma mean String or Number dispersion value identity or log mixture formula x_1 |p_1 + x_2|p_2 ... x_n| p_n NA NA negBinomial mean String or Number dispersion value identity or log nonrandom formula String or Number NA NA normal mean String or Number variance NA noZeroPoisson mean String or Number NA identity or log poisson mean String or Number NA identity or log uniform range from;to NA NA uniformInt range from;to NA NA

## Mixture

The mixture distribution makes it possible to mix to previously defined distributions/variables. Each variable that should be part of the new distribution x_1,...,X_n is assigned a probability p_1,...,p_n. For more information see rdatagen.net.

## Examples

ext_var <- 2.9
def <- defData(varname = "external", formula = "3 + log(..ext_var)", variance = .5)
def
#>     varname            formula variance   dist     link
#> 1: external 3 + log(..ext_var)      0.5 normal identitygenData(5, def)
#>    id external
#> 1:  1 4.864108
#> 2:  2 3.665887
#> 3:  3 5.448120
#> 4:  4 3.531613
#> 5:  5 5.689579