```r
starwars %>%
  filter(!is.na(species)) %>%
  group_by(species, gender) %>%
  summarise(ave_height = mean(height, na.rm = TRUE), var_height = var(height, na.rm = TRUE), n_obs = n()) %>%
  filter(n_obs > 1)
```

```
## # A tibble: 8 x 5
## # Groups:   species [6]
##   species  gender ave_height var_height n_obs
##   <chr>    <chr>       <dbl>      <dbl> <int>
## 1 Droid    none         200        NA       2
## 2 Droid    <NA>         120      1657       3
## 3 Gungan   male         209.      201.      3
## 4 Human    female       160.       48.8     9
## 5 Human    male         182.       67.1    26
## 6 Mirialan female       168         8       2
## 7 Wookiee  male         231        18       2
## 8 Zabrak   male         173         8       2
```