Individuals who heavily use social media tend to score more poorly on tests administered by psychologists to measure happiness than those who do not. It has been found that experiencing “status envy,” a state afflicting those who see themselves as being worse off than others—especially common among those who make use of social media—depletes the brain of chemicals responsible for feelings of joy and contentment. Obviously, there is a causal relationship: Extensive use of social media must be making people unhappy.
Which of the following, if true, most seriously undermines the force of the evidence given as support for the hypothesis that social media promotes unhappiness?