`tidy` and `glance` methods

[vincentarelbundock]

I am the developer of the modelsummary package which creates summary tables and plots for statistical models.

To extract info from fitted model, this package uses tidy and glance methods which conform to the broom standard: https://broom.tidymodels.org/

The broom standard is nice because it gives users a single unified interface to extract info from various objects. I'm opening this issue in case you think it would be a good idea to include such methods in your package. The benefit is that your objects would be automatically supported by packages like modelsummary and gtsummary and texreg. Users could then do this:

library(mitml)
library(lme4)
library(modelsummary)

data(studentratings)
fml <- ReadAchiev + ReadDis + SchClimate ~ 1 + (1|ID)
imp <- panImpute(studentratings, formula = fml, silent = TRUE, m = 24)
implist <- mitmlComplete(imp, "all")
fit <- with(implist, lmer(ReadAchiev ~ 1 + ReadDis + (1|ID)))

modelsummary(fit)

Here are minimal working methods:

tidy.mitml.result <- function(x, ...) {
    out <- testEstimates(x)
    out <- as.data.frame(out$estimates[, c(1:3, 5)])
    colnames(out) <- c("estimate", "std.error", "statistic", "p.value")
    out$term <- row.names(out)
    return(out)
}

glance.mitml.result <- function(x, ...) {
    data.frame(nimp = length(x),
               nobs = nobs(x[[1]]))
}

[simongrund1]

Thanks. I think this is a good idea, but I was wondering: Shouldn't these methods be included in broom instead? This seems to be the intended way of expanding the scope of tidy and glance methods (including them in mitml might lead to duplicate methods in the future). I'm going to close this issue for now, but I can reopen and you're of course also welcome to create a PR on the broom repo.

Some remarks on the methods:

1. I would prefer if these methods were defined for class mitml.testEstimates (the pooled results) rather than mitml.result (the individual results) and similar methods could be included for mitml.testModels (the output from pooled model comparisons). From what I see, the only disadvantage would be the lack of an "nobs", but this could be replaced with the df.com slot (if non-NULL).

2. The tidy method should ideally refer to the columns by name, and I think some options to include the degrees of freedom and FMI per parameter would be useful.

3. testEstimates(..., extra.pars = TRUE) also gives additional results depending on the model type. I'm not sure how best to deal with these, but it'd be great if they were included.

[vincentarelbundock]

Thanks for the suggestions!

Currently, the broom developers (mostly) do not merge in new methods, and instead recommend that modeling package developers supply their own methods (loading the dependency-free and very thin generics package).

FWIW, I do not use mitml myself, so I am unlikely to work on PR, and it's perfectly fine if you prefer to close this.

Thanks for releasing open source software!