# hw13 - STATISTICS 500 – Fall 2009 Homework 13 handed out...

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Unformatted text preview: STATISTICS 500 – Fall 2009 Homework 13 - handed out Weds, 9 Dec 2009 answers will be posted ca Thursday evening (10 Dec) Most (or all) parts of these problems can be done either in SAS or by hand. You are free to use the computer, but you should understand how to do them by hand. Parts of problem 4 are tedious. I suggest you make sure you know how do the calculations then look at the answers to see the point I’m trying to make. 1. Analysis of boy/girl ratios in families has always been of great interest to sociologists and evolutionary geneticists. Apparently, there are wonderful historical records kept in Germany and predecessor states. One study looked at 7200 19th century families in what is now Germany with 6 children in each family. Those families had 43,200 children, 20,937 were girls and 22,263 were boys. (a) Assume that all of the children (6*7200 = 43200) can be viewed as a sample from a single population with proportion of females equal to π . Test the hypothesis that π = 0 . 5. Give the P-value and give a one-sentence conclusion. (b) Estimate π and calculate a 95% confidence interval. (c) As part of the same study, 612 families with 12 children each were surveyed. Of these 7,344 children, 3534 were girls and 3810 were boys. Test whether the proportion of female children is different in 6-child families and 12-child families. Calculate a confidence interval for the difference. (d) If some families tended to ’maleness’ and others to ’femaleness’, i.e. P[child is male] varies between families, are the tests and confidence intervals reasonable? Explain why or why not....
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hw13 - STATISTICS 500 – Fall 2009 Homework 13 handed out...

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