A study showed the same level of T cell production in senior citizens who are amateur cyclists as in young adults, but a significantly lower level of T cell production in senior citizens who do not exercise regularly. Is it appropriate to infer that exercise stimulates T cell production? Explain. (Source: University of Birmingham)

Verified step by step guidance

1. Step 1: Begin by identifying the type of study described in the problem. This appears to be an observational study, as it compares T cell production levels across different groups without actively manipulating variables.
2. Step 2: Understand the key groups being compared: senior citizens who are amateur cyclists, senior citizens who do not exercise regularly, and young adults. Note that the study observes differences in T cell production levels among these groups.
3. Step 3: Consider the concept of causation versus correlation. While the study shows an association between exercise and higher T cell production in senior citizens, it does not establish causation because other factors (e.g., diet, genetics, or overall health) could influence T cell production.
4. Step 4: Reflect on the limitations of observational studies. Without a controlled experiment (e.g., randomly assigning participants to exercise or non-exercise groups), it is not possible to definitively infer that exercise stimulates T cell production.
5. Step 5: Conclude that while the study provides evidence of a correlation between exercise and T cell production, further experimental research would be needed to establish causation and confirm that exercise directly stimulates T cell production.

Key Concepts

Causation vs. Correlation

Causation refers to a direct cause-and-effect relationship between two variables, while correlation indicates a relationship where two variables change together but do not necessarily influence each other. In this context, while the study shows a correlation between exercise and T cell production, it does not definitively prove that exercise causes increased T cell production.

Control Groups

Control groups are essential in experimental studies as they provide a baseline for comparison. In this study, senior citizens who do not exercise serve as a control group, allowing researchers to assess the impact of exercise on T cell production. Without a control group, it would be challenging to determine whether the observed effects are due to exercise or other factors.

Statistical Significance

Statistical significance helps determine whether the results of a study are likely due to chance or represent a true effect. In this study, the significant difference in T cell production between exercising and non-exercising seniors suggests that exercise may have an impact, but further research is needed to establish a causal link and rule out confounding variables.