## Biostatistics

Biostatistics

Find the critical z values. In each case, assume that the normal distribution applies.

#19.)a = 0.02; isH1 is p < 0.19

#17.) In the article “Sex and Gender Bias in Anatomy and Physical Diagnosis Text Illustrations”, it is claimed that “males are depicted in a majority of nonreproductive anatomy illustrations.” Using the seven most popular anatomy textbooks and ignoring illustrations that were gender neutral, there are 142 nonreproductive illustrations based on females, and there are 554 nonreproductive illustrations based on males. Use a 0.05 significance level to test the claim that males are depicted in a majority of the nonreproductive illustrations.

#11.) When people smoke, the nicotine they absorb is converted to cotinine, which can be measured. A sample of 40 smokers has a mean cotinine level of 172.5. Assuming s is known to be 119.5, use a 0.01 significance level to test the claim that the mean cotinine level of all smokers is equal to 200.0.

#15.) A set of 20 values with a mean of 4.4 inches and a standard deviation of 4.2 inches. Use a 0.01 significance level to test the claim that the mean difference is greater than 0. Do the results support a sociologist’s claim that women tend to marry men who are taller than themselves?

#7.) In s study of women and heart disease, the following sample results were obtained: Among 10,239 women with a low level of physical activity (less than 200kcal/week), there were 101 cases of heart disease. Among 9877 women with physical activity measured between 200 and 600kcal/week, there were 56 cases of heart disease. Construct a 90% confidence interval estimate for the difference between the two proportions. Does the difference appear to be substantial? Does it appear that physical activity corresponds to a lower rate of heart disease?

#13.) Those convicted of arson, 50 were drinkers and 43 abstained. Of those convicted of fraud, 63 were drinkers, and 144 abstained. Use a 0.01 significance level to test the claim that the proportion of drinkers among convicted arsonists is greater than the proportion of drinkers convicted of fraud. Does it seem reasonable that drinking might have had an effect on the type of crime? Why?

#5.) Use a 0.01 significance level to test the claim that the population of heavy marijuana users has a lower mean than the light users. Should marijuana use be of convern to college students?

Items sorted correctly by light marijuana users: n=64, x? =53.3, s=3.6

Items sorted correctly by heavy marijuana users: n=65, x?= 51.3, s=4.5

#7.) People send huge sums of money (Currently around \$5 billion annually) for the purchase of magnets used to treat a wide variety of pains. Researches conducted a study to determine whether magnets are effective in treating back pain Pain was measured using the visual analog scale, and the results given below are among the results obtained in the study. Construct a 90% confidence interval estimate of the difference between the mean reduction in pain for those treated with magnets and the mean reduction in pain for those given a sham treatment. Based on the result, does it appear that the magnets are effective in reducing pain?

Reduction in pain level after magnet treatment: n=20, x?=0.49, s=0.96

Reduction in pain level after sham treatment: n=20, x?=0.44, s=1.4