When people engage in activities that help others, their brain releases endorphins, the brain’s natural opiates, which induce in people a feeling of well-being. It has been suggested that regular release of endorphins increases people’s longevity, and a statistic on adults who regularly engage in volunteer work helping others shows that they live longer, on average, than adults who do not volunteer. However, that statistic would be what we would expect even if volunteering does not boost longevity, because .

The study group was skewed

Explanation:

It is often touted that doing volunteer work would enhance life and life quality. While this is believed to be true and my have some substance to it, the design flaw of the experiments made it almost not credible.

The test group that was used were women who were engaged in volunteer work already. It has been shown that women are already living longer than men. To correlate the fact that people live longer who do volunteer work when only using a certain demographic may not be the most sound conclusion to make.

a factory opens that mass-produces light bulbs.

explanation:

not sure if that's an answer to your questions but this is an example! : )