This is a convenience function that helps automate the process of generating predicted data from regression model from a predictor(s). It is designed to give you the data frame for the predict method's newdata argument.

make_new_data(model, pred, pred.values = NULL, at = NULL,
  data = NULL, center = TRUE, set.offset = NULL, num.preds = 100)

Arguments

model

The model (e.g., lm, glm, merMod, svyglm)

pred

The name of the focal predictor as a string. This is the variable for which, if you are plotting, you'd likely have along the x-axis (with the dependent variable as the y-axis).

pred.values

The values of pred you want to include. Default is NULL, which means a sequence of equi-spaced values over the range of a numeric predictor or each level of a non-numeric predictor.

at

If you want to manually set the values of other variables in the model, do so by providing a named list where the names are the variables and the list values are vectors of the values. This can be useful especially when you are exploring interactions or other conditional predictions.

data

The data frame used in fitting the model. Default is NULL, in which case the data will be retrieved via model.frame or, if there are variable transformations in the formula, by looking in the environment for the data.

center

Set numeric covariates to their mean? Default is TRUE. You may also just provide a vector of names (as strings) of covariates to center. Note that for svyglm models, the survey-weighted means are used. For models with weights, these are weighted means.

set.offset

If the model has an offset, the value to use for the offset variable. Default is NULL, in which case the median of the offset variable is used.

num.preds

The number of predictions to generate. Default is 100. Ignored if pred.values is not NULL.

Value

A data frame.

Details

Please bear in mind that this does not generate the predictions. You will need to do that with a predict function for your model or another interface, such as the prediction package's titular function.

Examples

fit <- lm(Income ~ Frost + Illiteracy + Murder, data = as.data.frame(state.x77)) # Basic use new_data <- make_new_data(fit, pred = "Frost") # Set covariate to specific value new_data <- make_new_data(fit, pred = "Frost", at = list(Murder = 5)) # Set covariate to several specific values new_data <- make_new_data(fit, pred = "Frost", at = list(Murder = c(5, 10, 15)))