Question

a hypothetical cohort study was undertaken among 600 adhd - free children in south carolina. the purpose of the study was to examine the effects of increased screen - time during childhood on the subsequent diagnosis of adhd by young adulthood. the childrens screen time was assessed by a questionnaire, and the children were followed for 10 years. the following data were obtained from the study. calculate the appropriate measure of association between childhood screen time and adhd from question. round to the nearest hundredth. add your answer integer, decimal, or e notation allowed

Explanation:

Step1: Calculate the incidence of ADHD in the high - screen - time group

The incidence of ADHD in the group with 4 or more hours of screen time per day ($I_{1}$) is calculated as the number of ADHD cases in this group divided by the total number of people in this group.
$I_{1}=\frac{160}{285}\approx0.5614$

Step2: Calculate the incidence of ADHD in the low - screen - time group

The incidence of ADHD in the group with less than 4 hours of screen time per day ($I_{2}$) is calculated as the number of ADHD cases in this group divided by the total number of people in this group.
$I_{2}=\frac{140}{315}\approx0.4444$

Step3: Calculate the relative risk (RR)

The relative risk (RR) is the ratio of the incidence in the exposed group ($I_{1}$) to the incidence in the non - exposed group ($I_{2}$).
$RR = \frac{I_{1}}{I_{2}}=\frac{\frac{160}{285}}{\frac{140}{315}}=\frac{160\times315}{285\times140}=\frac{50400}{39900}\approx1.26$

Answer:

$1.26$