```r
starwars %>%
  filter(!is.na(species)) %>%
  group_by(species) %>%
  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 4
##   species  ave_height var_height n_obs
##   <chr>         <dbl>      <dbl> <int>
## 1 Droid          140       2705.     5
## 2 Gungan         209.       201.     3
## 3 Human          177.       157.    35
## 4 Kaminoan       221        128      2
## 5 Mirialan       168          8      2
## 6 Twi'lek        179          2      2
## 7 Wookiee        231         18      2
## 8 Zabrak         173          8      2
```