Researchers want to investigate the relationship between spe…

Reseаrchers wаnt tо investigаte the relatiоnship between spending time оutside and happiness. They ask the first 500 people they see how many minutes they spend outside per day and how happy they feel on a scale of 1-10, with 1 meaning "Not at all happy" and 10 meaning "Extremely happy".  Results show a statistically significant relationship between time spent outside and happiness, such that as people spend more time outside, they are happier. Therefore, researchers conclude that spending more time outside causes happiness. Is this conclusion justified?