In the illustrated argument the author has concluded from a survey on adults that to ameliorate well-being; people should strictly limit the time they spend online. In order to justify the argument, author has stated a study which reported that adults spending more than 30 hours online each week were found with the symptoms of depression. And it was deducted that because of spending much time online they were finding trouble in concentrating and feeling sad, down, or blue. However, the evidence author has presented look cogent at the first glance; they are based on some vague assumptions. It would be perfunctory to deduce the result without analysis of possible factors.
Firstly, the data of finding symptoms of depressing in the adults is having no particular reason. Author has assumed that this symptoms were the result of excessive use of internet. There are also possibilities of other reasons. Maybe those adults surveyed were having job issues, or family issues. It could be possible that they were finding difficulties in financial or social level. Who were the adults? Maybe they were working for computer tech company or a company in which they have to work online. And that is the reason why they were online for more than average time. If it is their work to be online than the solution is meaning less.
Secondly, problem in keeping concentration was reported. But being online can not be resulted in lack of concentration. Maybe the other environment factor was behind this fault. And how the conclusion was justified? If its was deduced by a common test then may be apathy for the test subject is the reason. 20 percent adults reported of feeling sad or blue three times withing the past month. But what were their condition before. Have they never felt such change before or maybe they have noticed because they were asked to. To compare without past data it can not be a strong reason to conclusion.
Summing up, all the facts and studies presented for the conclusion are questionable. Further analysis is needed. To strengthen the argument author needs some data about the nature of study, profession of adults surveyed, a glance at possible factors behind the concentrating effect and the clear social financial factors affecting mood. Past data of the studies is also required.