CHAPTER 6. INFERENCE FOR CATEGORICAL DATA 6.28 Prenatal vitamins and Autism. Researchers studying the link between prenatal vitamin use and autism surveyed the mothers of a random sample of children aged 24 - 60 months with autism and conducted another separate random sample for children with typical development. The table below shows the number of mothers in each group who did and did not use prenatal vitamins during the three months before pregnancy (periconceptional period). 29 Autism Autism Typical development Total Periconceptional No vitamin 111 70 181 prenatal vitamin Vitamin 143 159 302 Total 254 229 483 (a) State appropriate hypotheses to test for independence of use of prenatal vitamins during the three months before pregnancy and autism. (b) Complete the hypothesis test and state an appropriate conclusion. (Reminder: Verify any necessary conditions for the test.) (c) A New York Times article reporting on this study was titled "Prenatal Vitamins May Ward Off Autism". Do you find the title of this article to be appropriate? Explain your answer. Additionally, propose an alternative title. 30 6.29 HIV in sub-Saharan Africa. In July 2008 the US Nati