Fit mixed model to averages and apply trend to original data

Used within predict_lme4_avg_trend(), this function fits the model to the data frame, working whether the model is being fit across the entire data frame or being fit to each group individually. Data is filtered prior to fitting, model(s) are fit, and then fitted values are generated on the original.

Usage

fit_lme4_average_model(
  df,
  model,
  formula,
  average_cols,
  weight_col,
  ...,
  formula_vars,
  test_col,
  group_col,
  group_models,
  sort_col,
  sort_descending,
  pred_col,
  pred_upper_col,
  pred_lower_col,
  filter_na,
  ret,
  error_correct,
  error_correct_cols,
  shift_trend
)

Arguments

df: Data frame of model data.
model: An lme4 function that outputs a merMod object with that can be passed to merTools::predictInterval(). This should be one of lme4::lmer(), lme4::glmer(), or lme4::nlmer().
formula: A formula that will be supplied to the model, such as y~x.
average_cols: Column name(s) of column(s) for use in grouping data for averaging, such as regions. If missing, uses global average of the data for infilling.
weight_col: Column name of column of weights to be used in averaging, such as country population.
...: Other arguments passed to the model function.
formula_vars: Variables included in the model formula, generated by all.vars(formula).
test_col: Name of logical column specifying which response values to remove for testing the model's predictive accuracy. If NULL, ignored. See model_error() for details on the methods and metrics returned.
group_col: Column name(s) of group(s) to use in dplyr::group_by() when supplying type, calculating mean absolute scaled error on data involving time series, and if group_models, then fitting and predicting models too. If NULL, not used. Defaults to "iso3".
group_models: Logical, if TRUE, fits and predicts models individually onto each group_col. If FALSE, a general model is fit across the entire data frame.
sort_col: Column name(s) to use to dplyr::arrange() the data prior to supplying type and calculating mean absolute scaled error on data involving time series. If NULL, not used. Defaults to "year".
sort_descending: Logical value on whether the sorted values from sort_col should be sorted in descending order. Defaults to FALSE.
pred_col: Column name to store predicted value.
pred_upper_col: Column name to store upper bound of confidence interval generated by the predict_... function. This stores the full set of generated values for the upper bound.
pred_lower_col: Column name to store lower bound of confidence interval generated by the predict_... function. This stores the full set of generated values for the lower bound.
filter_na: Character value specifying how, if at all, to filter NA values from the dataset prior to applying the model. By default, all observations with missing values are removed, although it can also remove rows only if they have missing dependent or independent variables, or no filtering at all.
ret: Character vector specifying what values the function returns. Defaults to returning a data frame, but can return a vector of model error, the model itself or a list with all 3 as components.
error_correct: Logical value indicating whether or not whether mean error should be used to adjust predicted values. If TRUE, the mean error between observed and predicted data points will be used to adjust predictions. If error_correct_cols is not NULL, mean error will be used within those groups instead of overall mean error.
error_correct_cols: Column names of data frame to group by when applying error correction to the predicted values.
shift_trend: Logical value specifying whether or not to shift predictions so that the trend matches up to the last observation. If error_correct and shift_trend are both TRUE, shift_trend takes precedence.

Value

List of mdl (fitted model) and df (data frame with fitted values and confidence bounds generated from the model).

Details

If fitting models individually to each group, mdl will never be returned, as as these are instead a large group of models. Otherwise, a list of mdl and df is returned and used within predict_lme4_mdl().