Data, Sampling, and Variation in Data and Sampling · Exercise 28

Use the following data to answer the next five exercises: A pair of studies was performed to measure the effectiveness of a new software program designed to help stroke patients regain their problem-solving skills. Patients were asked to use the software program twice a day, once in the morning and once in the evening. The studies observed 200 stroke patients recovering over a period of several weeks. The first study collected the data in. The second study collected the data in.
$$\begin{array}{cccc}\text{Group}& \text{Showed improvement}& \text{No improvement}& \text{Deterioration}\\ \text{Used program}& \text{142}& \text{43}& \text{15}\\ \text{Did not use program}& \text{72}& \text{110}& \text{18}\end{array}$$
$$\begin{array}{cccc}\text{Group}& \text{Showed improvement}& \text{No improvement}& \text{Deterioration}\\ \text{Used program}& \text{105}& \text{74}& \text{19}\\ \text{Did not use program}& \text{89}& \text{99}& \text{4}\end{array}$$

Patients who used the software were also a part of an exercise program whereas patients who did not use the software were not. Does this change the validity of the conclusions from?

OpenStax, Introductory Statistics 2e · §1.2 Data, Sampling, and Variation in Data and Sampling · Exercise 28