Question

A recent study shows that just one session of cognitive behavioral therapy can help people with insomnia. \({ }^{16}\) In the study, forty people who had been diagnosed with insomnia were randomly divided into two groups of 20 each. People in one group received a one-hour cognitive behavioral therapy session while those in the other group received no treatment. Three months later, 14 of those in the therapy group reported sleep improvements while only 3 people in the other group reported improvements. (a) What are the cases in this study? (b) What are the relevant variables? Identify each as categorical or quantitative. (c) If we create a dataset of the information with cases as rows and variables as columns, how many rows and how many columns would the dataset have?

Short answer

(a) The cases in this study are the 40 individuals diagnosed with insomnia. (b) The relevant variables are whether an individual received cognitive behavioral therapy (categorical) and whether they reported sleep improvements (categorical). (c) The data set would contain 40 rows and 2 columns.

Step-by-step solution

Identify the Cases

Cases in a study are the individual units of observation. In this study, the cases are the 40 people who have been diagnosed with insomnia and were divided into two groups.

Identify the Variables

Variables are characteristics that can take on different values for different cases. Here the variables include whether an individual received cognitive behavioral therapy (categorical variable: yes or no) and whether the individual reported sleep improvements three months later (categorical variable: yes or no).

Count Rows and Columns in the Dataset

If we create a dataset using this information, each row would represent a unique case – in this case, each individual participant in the study. Hence, the dataset would have 40 rows. The columns correspond to the variables we've identified. Here, there are two variables, so the dataset would have two columns.