Crosstabs

# Crosstabs

Sometimes you want your results in a crosstab. We can use the `tabyl` function in `janitor` package to make crosstabs automatically.

Create a crosstab of `gender` and `health_gen`. 


```{r}
nhanes %>% 
  tabyl(gender, health_gen) 
```

Add a `drop_na` before your line with `tabyl` to get rid of all NAs.

```{r}
nhanes %>% 
  drop_na(gender, health_gen) %>% 
  tabyl(gender, health_gen) 
```


`janitor` has a set of functions that all start with `adorn_` that add a number of things to our crosstabs. We call them after `tabyl`. For example, `adorn_totals`.

Use the code above and then add totals using `adorn_totals` in the rows and columns.

```{r}
nhanes %>% 
  drop_na(gender, health_gen) %>% 
  tabyl(gender, health_gen) %>% 
  adorn_totals(where = c("row", "col"))
```


We can add `adorn_percentages` to add percentages.

Use the code above and then add percentages using `adorn_percentages`.


```{r}
nhanes %>% 
  drop_na(gender, health_gen) %>% 
  tabyl(gender, health_gen) %>% 
  adorn_totals(where = c("row", "col")) %>% 
  adorn_percentages()
```



We can then format these percentages using `adorn_pct_formatting`.

Use the code above and then format the percentages using `adorn_pct_formatting`. Add arguments so that the percentages are rounded to 1 digit. Note that R uses the "half to even" rounding method by default so if you want to round, say, 14.5 to 15 you must use the `rounding` argument (type ?adorn_pct_formatting in the console to learn more). 

```{r}
nhanes %>% 
  drop_na(gender, health_gen) %>% 
  tabyl(gender, health_gen) %>% 
  adorn_totals(where = c("row", "col")) %>% 
  adorn_percentages() %>% 
  adorn_pct_formatting(digits = 1, 
                       rounding = "half up") 
```



If we want to include the n alongside percentages, we can use `adorn_ns`.

Use the code above and then add a line with `adorn_ns` to include the n.

```{r}
nhanes %>% 
  drop_na(gender, health_gen) %>% 
  tabyl(gender, health_gen) %>% 
  adorn_totals(c("row", "col")) %>% 
  adorn_percentages() %>% 
  adorn_pct_formatting(digits = 1, 
                       rounding = "half up") %>% 
  adorn_ns()
```



We can add titles to our crosstabs using `adorn_title`.

Use the code above and then add a title using `adorn_title`. Use the `placement` argument and see what you get.

```{r}
nhanes %>% 
  drop_na(gender, health_gen) %>% 
  tabyl(gender, health_gen) %>% 
  adorn_totals(c("row", "col")) %>% 
  adorn_percentages() %>% 
  adorn_pct_formatting(digits = 0, 
                       rounding = "half up") %>% 
  adorn_ns() %>% 
  adorn_title(placement = "combined")
```




We can also do three (or more) way crosstabs automatically by adding more variables to the `tabyl` function.

Use the code above, but add a third variable (`age_decade`) to the line with `drop_na` and the line with `tabyl`. You should get a series of crosstabs.

```{r}
nhanes %>% 
  drop_na(gender, health_gen, age_decade) %>% 
  tabyl(gender, health_gen, age_decade) %>% 
  adorn_totals(c("row", "col")) %>% 
  adorn_percentages() %>% 
  adorn_pct_formatting(digits = 0, rounding = "half up") %>% 
  adorn_ns() %>% 
  adorn_title()

```