statistics.

ADHD? OR JUST YOUNGEST IN THE CLASS? A study indicates that the youngest children in a school grade are more likely to be diagnosed with attention-deficit/hyperactivity disorder (ADHD) than their older peers in the same grade. The study involved 937,943 children between 6 and 12 years old in British Columbia, Canada. The cutoff date for entering school in any year in British Columbia is December 31st, so in any given class, those born late in the year are almost a year younger than those born early in the year. Is it possible that the younger students are being over-diagnosed with ADHD? Girls are less likely overall to be diagnosed with ADHD but does the same relationship exist with relative age in school? Girls: ADHD or Just Young? The table below shows the number of girls diagnosed with ADHD based on the quarter of the year in which they were born, as well as the proportion of girls born during that quarter. Birth Date ADHD Diagnoses Proportion of Births Jan-Mar 1960 0.243 Apr-Jun 2358 0.258 Jul-Sep 2859 0.257 Oct-Dec 2904 0.242 Table 1 ADHD diagnoses and relative age for girls(a) What is the total number of girls diagnosed with ADH D in the sample? Total number of girls = n (b) For the null hypothesis, use the overall proportion of births in a quarter to give the null proportion for that quarter. Compute the expected number of ADH D diagnoses for each quarter under this hypothesis. Round your answers to one decimal place. JanMar = n AprJun = n Jul-Sep = n Oct-Dec = n (c) Compute the ,(z statistic. Round your answer to one decimal place. zen (d) Give the degrees of freedom and nd the pvalue. Enter the exact answer for the degrees of freedom, and round your answer for the pvalue to three decimal places. df = n p-value= n