R/check_model_diagnostics.R

In performance: Assessment of Regression Models Performance

# prepare data for VIF plot ----------------------------------

.diag_vif <- function(model, verbose = TRUE) {
  out <- check_collinearity(model, verbose = verbose)
  dat <- insight::compact_list(out)
  if (is.null(dat)) {
    return(NULL)
  }
  dat$group <- "low"
  dat$group[dat$VIF >= 5 & dat$VIF < 10] <- "moderate"
  dat$group[dat$VIF >= 10] <- "high"

  dat <- datawizard::data_rename(
    dat,
    c("Term", "VIF", "SE_factor", "Component"),
    c("x", "y", "se", "facet"),
    verbose = FALSE
  )

  dat <- datawizard::data_select(
    dat,
    c("x", "y", "facet", "group"),
    verbose = FALSE
  )

  if (insight::n_unique(dat$facet) <= 1) {
    dat$facet <- NULL
  }

  attr(dat, "CI") <- attributes(out)$CI
  dat
}



# prepare data for QQ plot ----------------------------------

.diag_qq <- function(model, verbose = TRUE) {
  if (inherits(model, c("lme", "lmerMod", "merMod", "glmmTMB", "gam"))) {
    res_ <- stats::residuals(model)
  } else if (inherits(model, "geeglm")) {
    res_ <- stats::residuals(model, type = "pearson")
  } else if (inherits(model, "glm")) {
    res_ <- .safe(abs(stats::rstandard(model, type = "deviance")))
  } else {
    res_ <- .safe(stats::rstudent(model))
    if (is.null(res_)) {
      res_ <- .safe(stats::residuals(model))
    }
  }

  if (is.null(res_)) {
    if (verbose) {
      insight::format_alert(
        sprintf(
          "QQ plot could not be created. Cannot extract residuals from objects of class `%s`.",
          class(model)[1]
        )
      )
    }
    return(NULL)
  }

  if (inherits(model, "glm")) {
    fitted_ <- stats::qnorm((stats::ppoints(length(res_)) + 1) / 2)
  } else {
    fitted_ <- stats::fitted(model)
  }

  # validation check, sometimes either residuals or fitted can contain NA, see #488
  if (anyNA(res_) || anyNA(fitted_)) {
    # drop NA and make sure both fitted and residuals match
    non_na <- !is.na(fitted_) & !is.na(res_)
    fitted_ <- fitted_[non_na]
    res_ <- res_[non_na]
  }

  res_ <- sort(res_, na.last = NA)
  fitted_ <- sort(fitted_, na.last = NA)

  data.frame(x = fitted_, y = res_)
}



# prepare data for random effects QQ plot ----------------------------------

.diag_reqq <- function(model, level = 0.95, model_info = NULL, verbose = TRUE) {
  # check if we have mixed model
  if (is.null(model_info) || !model_info$is_mixed) {
    return(NULL)
  }

  insight::check_if_installed("lme4")

  tryCatch(
    {
      if (inherits(model, "glmmTMB")) {
        var_attr <- "condVar"
        re <- .collapse_cond(lme4::ranef(model, condVar = TRUE))
      } else {
        var_attr <- "postVar"
        re <- lme4::ranef(model, condVar = TRUE)
      }
    },
    error = function(e) {
      return(NULL)
    }
  )


  se <- tryCatch(
    {
      suppressWarnings(lapply(re, function(.x) {
        pv <- attr(.x, var_attr, exact = TRUE)
        cols <- seq_len(dim(pv)[1])
        unlist(lapply(cols, function(.y) sqrt(pv[.y, .y, ])))
      }))
    },
    error = function(e) {
      NULL
    }
  )

  if (is.null(se)) {
    if (verbose) {
      insight::format_alert("Could not compute standard errors from random effects for diagnostic plot.")
    }
    return(NULL)
  }


  Map(function(.re, .se) {
    ord <- unlist(lapply(.re, order)) + rep((0:(ncol(.re) - 1)) * nrow(.re), each = nrow(.re))

    df.y <- unlist(.re)[ord]
    df.ci <- stats::qnorm((1 + level) / 2) * .se[ord]

    data.frame(
      x = rep(stats::qnorm(stats::ppoints(nrow(.re))), ncol(.re)),
      y = df.y,
      conf.low = df.y - df.ci,
      conf.high = df.y + df.ci,
      facet = gl(ncol(.re), nrow(.re), labels = names(.re)),
      stringsAsFactors = FALSE,
      row.names = NULL
    )
  }, re, se)
}



# prepare data for normality of residuals plot ----------------------------------

.diag_norm <- function(model, verbose = TRUE) {
  r <- try(as.numeric(stats::residuals(model)), silent = TRUE)

  if (inherits(r, "try-error")) {
    insight::format_alert(sprintf(
      "Non-normality of residuals could not be computed. Cannot extract residuals from objects of class '%s'.",
      class(model)[1]
    ))
    return(NULL)
  }

  dat <- as.data.frame(bayestestR::estimate_density(r))
  dat$curve <- stats::dnorm(seq(min(dat$x), max(dat$x), length.out = nrow(dat)), mean(r), stats::sd(r))
  dat
}



# prepare data for influential obs plot ----------------------------------

.diag_influential_obs <- function(model, threshold = NULL) {
  s <- summary(model)

  if (inherits(model, "lm", which = TRUE) == 1) {
    cook_levels <- round(stats::qf(0.5, s$fstatistic[2], s$fstatistic[3]), 2)
  } else if (is.null(threshold)) {
    cook_levels <- c(0.5, 1)
  } else {
    cook_levels <- threshold
  }

  n_params <- tryCatch(model$rank, error = function(e) insight::n_parameters(model))

  infl <- stats::influence(model, do.coef = FALSE)
  resid <- as.numeric(insight::get_residuals(model))

  std_resid <- tryCatch(stats::rstandard(model, infl), error = function(e) resid)

  plot_data <- data.frame(
    Hat = infl$hat,
    Cooks_Distance = stats::cooks.distance(model, infl),
    Fitted = insight::get_predicted(model, ci = NULL),
    Residuals = resid,
    Std_Residuals = std_resid,
    stringsAsFactors = FALSE
  )
  plot_data$Index <- seq_len(nrow(plot_data))
  plot_data$Influential <- "OK"
  plot_data$Influential[abs(plot_data$Cooks_Distance) >= max(cook_levels)] <- "Influential"

  attr(plot_data, "cook_levels") <- cook_levels
  attr(plot_data, "n_params") <- n_params
  plot_data
}



# prepare data for non-constant variance plot ----------------------------------

.diag_ncv <- function(model, verbose = TRUE) {
  ncv <- tryCatch(
    {
      data.frame(
        x = as.numeric(stats::fitted(model)),
        y = as.numeric(stats::residuals(model))
      )
    },
    error = function(e) {
      NULL
    }
  )

  if (is.null(ncv)) {
    if (verbose) {
      insight::format_alert(sprintf(
        "Non-constant error variance could not be computed. Cannot extract residuals from objects of class '%s'.",
        class(model)[1]
      ))
    }
    return(NULL)
  }

  ncv
}



# prepare data for homogeneity of variance plot ----------------------------------

.diag_homogeneity <- function(model, verbose = TRUE) {
  faminfo <- insight::model_info(model)
  r <- tryCatch(
    {
      if (inherits(model, "merMod")) {
        stats::residuals(model, scaled = TRUE)
      } else if (inherits(model, "gam")) {
        stats::residuals(model, type = "scaled.pearson")
      } else if (inherits(model, c("glmmTMB", "MixMod"))) {
        sigma <- if (faminfo$is_mixed) {
          sqrt(insight::get_variance_residual(model))
        } else {
          .sigma_glmmTMB_nonmixed(model, faminfo)
        }
        stats::residuals(model) / sigma
      } else if (inherits(model, "glm")) {
        ## TODO: check if we can / should use deviance residuals (as for QQ plots) here as well?
        stats::rstandard(model, type = "pearson")
      } else {
        stats::rstandard(model)
      }
    },
    error = function(e) {
      NULL
    }
  )

  if (is.null(r)) {
    if (verbose) {
      insight::format_alert(sprintf(
        "Homogeneity of variance could not be computed. Cannot extract residual variance from objects of class '%s'.",
        class(model)[1]
      ))
    }
    return(NULL)
  }

  data.frame(
    x = stats::fitted(model),
    y = sqrt(abs(r))
  )
}



# prepare data for homogeneity of variance plot ----------------------------------

.diag_overdispersion <- function(model) {
  faminfo <- insight::model_info(model)

  # data for poisson models
  if (faminfo$is_poisson && !faminfo$is_zero_inflated) {
    d <- data.frame(Predicted = stats::predict(model, type = "response"))
    d$Residuals <- insight::get_response(model) - as.vector(d$Predicted)
    d$Res2 <- d$Residuals^2
    d$V <- d$Predicted
    d$StdRes <- insight::get_residuals(model, type = "pearson")
  }

  # data for negative binomial models
  if (faminfo$is_negbin && !faminfo$is_zero_inflated) {
    d <- data.frame(Predicted = stats::predict(model, type = "response"))
    d$Residuals <- insight::get_response(model) - as.vector(d$Predicted)
    d$Res2 <- d$Residuals^2
    d$V <- d$Predicted * (1 + d$Predicted / insight::get_sigma(model))
    d$StdRes <- insight::get_residuals(model, type = "pearson")
  }

  # data for zero-inflated poisson models
  if (faminfo$is_poisson && faminfo$is_zero_inflated) {
    d <- data.frame(Predicted = stats::predict(model, type = "response"))
    d$Residuals <- insight::get_response(model) - as.vector(d$Predicted)
    d$Res2 <- d$Residuals^2
    if (inherits(model, "glmmTMB")) {
      ptype <- "zprob"
    } else {
      ptype <- "zero"
    }
    d$Prob <- stats::predict(model, type = ptype)
    d$V <- d$Predicted * (1 - d$Prob) * (1 + d$Predicted * d$Prob)
    d$StdRes <- insight::get_residuals(model, type = "pearson")
  }

  # data for zero-inflated negative binomial models
  if (faminfo$is_negbin && faminfo$is_zero_inflated && !faminfo$is_dispersion) {
    d <- data.frame(Predicted = stats::predict(model, type = "response"))
    d$Residuals <- insight::get_response(model) - as.vector(d$Predicted)
    d$Res2 <- d$Residuals^2
    if (inherits(model, "glmmTMB")) {
      ptype <- "zprob"
    } else {
      ptype <- "zero"
    }
    d$Prob <- stats::predict(model, type = ptype)
    d$Disp <- insight::get_sigma(model)
    d$V <- d$Predicted * (1 + d$Predicted / d$Disp) * (1 - d$Prob) * (1 + d$Predicted * (1 + d$Predicted / d$Disp) * d$Prob) # nolint
    d$StdRes <- insight::get_residuals(model, type = "pearson")
  }

  # data for zero-inflated negative binomial models with dispersion
  if (faminfo$is_negbin && faminfo$is_zero_inflated && faminfo$is_dispersion) {
    d <- data.frame(Predicted = stats::predict(model, type = "response"))
    d$Residuals <- insight::get_response(model) - as.vector(d$Predicted)
    d$Res2 <- d$Residuals^2
    if (inherits(model, "glmmTMB")) {
      ptype <- "zprob"
    } else {
      ptype <- "zero"
    }
    d$Prob <- stats::predict(model, type = ptype)
    d$Disp <- stats::predict(model, type = "disp")
    d$V <- d$Predicted * (1 + d$Predicted / d$Disp) * (1 - d$Prob) * (1 + d$Predicted * (1 + d$Predicted / d$Disp) * d$Prob) # nolint
    d$StdRes <- insight::get_residuals(model, type = "pearson")
  }

  d
}



# helpers ----------------------------------

.sigma_glmmTMB_nonmixed <- function(model, faminfo) {
  if (!is.na(match(faminfo$family, c("binomial", "poisson", "truncated_poisson")))) {
    return(1)
  }
  betad <- model$fit$par["betad"]
  switch(faminfo$family,
    gaussian = exp(0.5 * betad),
    Gamma = exp(-0.5 * betad),
    exp(betad)
  )
}