Package: dplyr

Function: slice_sample()

1. Randomly choose 3 teachers per grade level

Review the data (d1)

# A tibble: 14 x 2
      id grade
   <dbl> <dbl>
 1    10     3
 2    11     3
 3    12     3
 4    13     4
 5    14     4
 6    15     4
 7    16     3
 8    17     3
 9    18     4
10    19     4
11    20     3
12    21     4
13    22     4
14    23     3

I want to send surveys out to 3 teachers per grade level so I want to randomly choose those teachers from our existing roster.

Let’s first see how many teachers we have per grade level.

d1 %>%
  janitor::tabyl(grade)
 grade n percent
     3 7     0.5
     4 7     0.5

Next we can create our random samples.

First we need to use base::set.seed() and choose any number to add as my seed. Setting this seed ensures that if I ever run this code again at a later time, I will get the same random sample each time. Very important!

Next we can use dplyr::group_by() to group our data by grade level and then use dplyr::slice_sample() to randomly select our cases. We use the argument n to say how many cases we want from each group.

base::set.seed(1234)

d1 %>%
  dplyr::group_by(grade) %>%
  dplyr::slice_sample(n = 3)
# A tibble: 6 x 2
# Groups:   grade [2]
     id grade
  <dbl> <dbl>
1    16     3
2    11     3
3    17     3
4    18     4
5    13     4
6    19     4

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