Social Media Use and ADHD. Exercise 2.23 introduces a study examining whether frequent use of digital social media during adolescence is associated with subsequent occurrence of ADHD symptoms. Researchers rated the frequency of digital social media use (high frequency or low frequency of use) of teens who were 15 or 16 years old and did not show symptoms of ADHD at the start of the study. They then followed the participants for two years, and recorded whether or not ADHD symptoms appeared. The results are shown in the table below. (a) Conduct a 2 test for association to see if frequency of social media use and diagnosis of ADHD are associated. Use a 5% significance level. Note here the pvalue for 3.841 is 0.05. (b) Which cell contributes the most to the chi-square statistic? In this cell, is the observed count greater than or less than the expected value? Interpret your result in terms of ADHD and social media use. (c) Can we conclude that higher social media use increases the likelihood of a diagnosis of ADHD?

Social media use and ADHA Diagnosis

Social media use	ADHD	NO ADHA	TOTAL
High frequency	16	149	165
Low frequency	23	472	495
total	39	621	660