This study is showing that many people perceive their jobs to be useless, but it neither asks for nor studies any factual basis for their perceptions. The study

This study is showing that many people perceive their jobs to be useless, but it neither asks for nor studies any factual basis for their perceptions. The study just assumes that certain jobs are "more useless" than others and looks for correlations between people's perceptions and those assumptions. In other words, all this study really shows is that the jobs of the people who did the study are basically useless, since they are producing no information that is of actual value.