---
title: "Model-based continuous summary tables in R"
description: >
  Build model-based summary tables for continuous outcomes in R with
  table_continuous_lm(), including estimated means, robust standard
  errors, case weights, and APA-style output formats.
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Model-based continuous summary tables in R}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

build_rich_tables <- identical(Sys.getenv("IN_PKGDOWN"), "true")

pkgdown_dark_gt <- function(tab) {
  tab |>
    gt::opt_css(
      css = paste(
        ".gt_table, .gt_heading, .gt_col_headings, .gt_col_heading,",
        ".gt_column_spanner_outer, .gt_column_spanner, .gt_title,",
        ".gt_subtitle, .gt_sourcenotes, .gt_sourcenote {",
        "  background-color: transparent !important;",
        "  color: currentColor !important;",
        "}",
        sep = "\n"
      )
    )
}
```

```{r setup}
library(spicy)
```

`table_continuous_lm()` is the model-based companion to
`table_continuous()`. It fits one linear model per selected continuous
outcome using `lm(outcome ~ by, ...)`, then returns a compact reporting
table. This makes it the better choice when you want to stay in a
linear-model workflow, add heteroskedasticity-consistent standard
errors, or apply case weights.

## Basic usage

Use `select` for one or more continuous outcomes and `by` for the
single predictor:

```{r basic}
table_continuous_lm(
  sochealth,
  select = c(wellbeing_score, bmi, life_sat_health),
  by = sex
)
```

For categorical predictors, the table reports estimated means by level.
When the predictor is dichotomous, it can also show a single mean
difference and confidence interval.

## Robust standard errors

Use `vcov = "HC*"` when you want heteroskedasticity-consistent standard
errors and tests:

```{r robust}
table_continuous_lm(
  sochealth,
  select = c(wellbeing_score, bmi),
  by = sex,
  vcov = "HC3",
  statistic = TRUE
)
```

## Case weights

Use `weights` when you want weighted estimated means or slopes in the
same model-based table:

```{r weights}
table_continuous_lm(
  sochealth,
  select = c(wellbeing_score, bmi),
  by = education,
  weights = weight
)
```

This is often the most natural summary-table function when your
reporting workflow already relies on weighted linear models.

## Numeric predictors

If `by` is numeric, `table_continuous_lm()` reports the slope rather
than group means:

```{r numeric-by}
table_continuous_lm(
  sochealth,
  select = c(wellbeing_score, bmi),
  by = age,
  vcov = "HC3",
  output = "long"
)
```

When you need the underlying returned data for further processing, use
`output = "data.frame"` for the wide raw table or `output = "long"` for
the analytic long table.

## Publication-ready output

The function supports the same output formats as the other summary-table
helpers, including `tinytable`, `gt`, `flextable`, `excel`, `word`, and
`clipboard`.

```{r gt-output, eval = build_rich_tables}
pkgdown_dark_gt(
  table_continuous_lm(
    sochealth,
    select = c(wellbeing_score, bmi, life_sat_health),
    by = sex,
    vcov = "HC3",
    statistic = TRUE,
    output = "gt"
  )
)
```

## See also

- See `vignette("table-continuous", package = "spicy")` for descriptive
  continuous summary tables with classical group-comparison tests.
- See `vignette("summary-tables-reporting", package = "spicy")` for a
  cross-function reporting workflow using the summary-table helpers.