sample_rmd.Rmd

---
title: "mtcars example markdown"
author: "Mike Frank"
date: "2023-03-21"
output: 
  html_document:
    toc: true
    toc_float: true
---

```{r echo=FALSE}
knitr::opts_chunk$set(echo = FALSE, warning = FALSE, 
                      message = FALSE, sanitize = TRUE)
```


```{r}
library(tidyverse)
```

# The `mtcars` dataset

```{r}
knitr::kable(mtcars)
```
# Analysis

## Visualization

```{r}
ggplot(mtcars, aes(x = mpg, y = hp, col = as.factor(cyl))) + 
  geom_point() + 
  geom_smooth(method = "lm")
```

## Statistical testing

```{r}
cars_t <- with(mtcars, 
     t.test(mpg[cyl == 8], 
            mpg[cyl == 4]) )

# cars_t$statistic
# cars_t$parameter
# cars_t$p.value
```

There are `r sum(mtcars$cyl == 8)` cars in the dataset with 8 cylinders, and `r sum(mtcars$cyl == 4)` cars with 4 cylinders. 

Cars with 8 cylinders have significantly lower gas mileage than cars with 4 cylinders (t(`r round(cars_t$parameter,2)`) = `r round(cars_t$statistic,2)`, p = `r round(cars_t$p.value,6)`).