Students often say "proof" or "researchers proved...". Here's a study that might get them re-thinking this tendency to use this word.
A study that appeared in the journal Neurology entitled, Midlife cardiovascular fitness and dementia
A 44-year longitudinal population study in women and nicely summarized here by CNN, did the following and found some convincing results:
Results: overall, 23% of the women developed dementia. However, 45% of those in the "low fitness" group developed dementia.
Proof, then, that exercise can prevent dementia?
Actually, this study, as impressively carried out as it is, cannot lead us to confident causal conclusions about the role of exercise in warding off dementia. The results are correlational at best and as we know, correlation is not causation.
Ask your students: are there alternative explanations for the results?
Have your students work in groups of 2-3 to see if they can generate some alternative hypotheses to the results. Here are some:
So while the study can be said to “provide some evidence” in favor of a causal link between exercise and dementia, it cannot offer “proof”. We really don’t know - for sure - what those high fitness women did in their lives that resulted in their lower levels of dementia.