A researcher has participants who are experienced or inexperienced with using computers complete a computer task that is either easy or difficult. He records stress levels among participants and finds...

A researcher has participants who are experienced or inexperienced with using computers complete a computer task that is either easy or difficult. He records stress levels among participants and finds a significant main effect of experience. He concludes that having experience with using computers causes participants to have lower stress levels compared to those who are inexperienced. Explain why this conclusion is inappropriate.