Virtual Sampling

We performed this sampling activity by hand first so that we can develop a firm understanding of the root ideas behind sampling. Now, we’ll mimic this tactile sampling activity with a virtual sampling activity. In other words, we’ll use a virtual analog to the bowl of balls and a virtual analog to the shovel.

Using the virtual shovel once

Let’s start by performing the virtual analog of the tactile sampling exercise we performed. We first need a virtual analog of the bowl. To this end, we included a data frame named bowl in the moderndive package. The rows of bowl correspond exactly with the contents of the actual bowl.

Observe that bowl has 2,400 rows, which tells us that the bowl contains 2,400 equally sized balls. The first variable ball_ID is used as an identification variable. None of the balls in the actual bowl are marked with numbers. The second variable color indicates whether a particular virtual ball is red or white. We’ll view the contents of the bowl and scroll through the contents to convince ourselves that bowl is indeed a virtual analog of the actual bowl.

Now that we’ve a virtual analog of our bowl, we now need a virtual analog to the shovel to generate virtual samples of 50 balls. We’re going to use the rep_sample_n() function included in the moderndive package. This function allows us to take repeated, or replicated, samples of size n.

Observe that the virtual_shovel has 50 rows corresponding to our virtual sample of size 50. The ball_ID variable identifies which of the 2,400 balls from bowl are included in our sample of 50 balls. Furthermore, the color variable denotes the color of the balls. However, what does ...