• Find and use the measures of center to explain the behavior of a data set

Feeling Sleepy!

Previously, we explored data from a study that asked college students whether they identified as owls, larks, or neither and collected other pieces of data related to academics, lifestyle, stress, and sleep.

Recall that owls were defined as night people while larks represented morning people. Using the data set from the study, we visualized categorical data via pie charts and bar graphs. Now, let’s use the same data set to explore distributions of quantitative variables. Let’s see how the mean and median can be used as numerical measures of the center of quantitative data!

Before we begin, consider the following research question, which asks about differences between larks and owls with respect to factors contributing to the quality of sleep.

Before we compare each of the groups (owl, lark, neither), let’s consider two variables of interest for all college students in this study:

• Poor Sleep Quality Score: A score indicating the average quality of sleep for the participants. The greater the score, the worse the quality of sleep.
• Number of Missed Classes: The average number of classes missed by the participants.

Making Comparisons Using Histograms

Histograms provide a good way of examining the distribution of values in one sample. Superimposing one histogram on another with the same range of values can help us compare the distribution of two or more samples.

Let’s look at another comparison using histograms. The following histograms illustrate the distributions of the Alcoholic Drinks per Week variable based on whether the participants identified as owls, larks, or neither.