Add likelihood ratio test and other methods, fixes

The likelihood ratio test method is lrtest, in addition,
methods for update and residuals were added.

1 files changed, 31 insertions, 0 deletions

diff --git a/R/residuals.mkinfit.R b/R/residuals.mkinfit.R
new file mode 100644
index 00000000..96bcf01c
--- /dev/null
+++ b/R/residuals.mkinfit.R
@@ -0,0 +1,31 @@
+#' Extract residuals from an mkinfit model
+#'
+#' @param object An \code{\link{mkinfit}} object
+#' @param standardized Should the residuals be standardized by dividing by the
+#'   standard deviation obtained from the fitted error model?
+#' @param \dots Not used
+#' @export
+#' @examples
+#' f <- mkinfit("DFOP", FOCUS_2006_C, quiet = TRUE)
+#' residuals(f)
+#' residuals(f, standardized = TRUE)
+residuals.mkinfit <- function(object, standardized = FALSE, ...) {
+  res <- object$data[["residual"]]
+  if (standardized) {
+    if (object$err_mod == "const") {
+      sigma_fitted <- object$errparms["sigma"]
+    }
+    if (object$err_mod == "obs") {
+      sigma_names = paste0("sigma_", object$data[["variable"]])
+      sigma_fitted <- object$errparms[sigma_names]
+    }
+    if (object$err_mod == "tc") {
+      sigma_fitted <- sigma_twocomp(object$data[["predicted"]],
+        sigma_low = object$errparms[1],
+        rsd_high = object$errparms[2])
+    }
+    return(res / sigma_fitted)
+  }
+  return(res)
+}
+