Returns the names of the predictor variables for the different parts of a model (like fixed or random effects, zero-inflated component, ...). Unlike find_parameters, the names from find_predictors() match the original variable names from the data that was used to fit the model.

  effects = c("fixed", "random", "all"),
  component = c("all", "conditional", "zi", "zero_inflated", "dispersion",
    "instruments", "correlation", "smooth_terms"),
  flatten = FALSE,
  verbose = TRUE,



A fitted model.


Should variables for fixed effects, random effects or both be returned? Only applies to mixed models. May be abbreviated.


Should all predictor variables, predictor variables for the conditional model, the zero-inflated part of the model, the dispersion term or the instrumental variables be returned? Applies to models with zero-inflated and/or dispersion formula, or to models with instrumental variable (so called fixed-effects regressions). May be abbreviated. Note that the conditional component is also called count or mean component, depending on the model.


Logical, if TRUE, the values are returned as character vector, not as list. Duplicated values are removed.


Toggle warnings.


Currently not used.


A list of character vectors that represent the name(s) of the predictor variables. Depending on the combination of the arguments effects and component, the returned list has following elements:

  • conditional, the "fixed effects" terms from the model

  • random, the "random effects" terms from the model

  • zero_inflated, the "fixed effects" terms from the zero-inflation component of the model

  • zero_inflated_random, the "random effects" terms from the zero-inflation component of the model

  • dispersion, the dispersion terms

  • instruments, for fixed-effects regressions like ivreg, felm or plm, the instrumental variables

  • correlation, for models with correlation-component like gls, the variables used to describe the correlation structure


m <- lm(mpg ~ wt + cyl + vs, data = mtcars)
#> $conditional
#> [1] "wt"  "cyl" "vs"