13.Use the following information to answer the questions below:

Research published in the journal Cough in 2012 examined the records of 241 children who visited a pediatrician with a severe cough. They found that coughing stopped in 47% of the 101 children who were treated with the non-opiate cough suppressant levodropropizine compared with 28% of the 60 children treated with cough suppressants containing opiates and 20% of the 80 children who were not prescribed anything for their coughs. The difference in cough relief was found to be statistically significant. However, in reviewing the study a critic pointed out that pediatricians are known to be hesitant to prescribe opiate based cough suppressants in very young children except in very specific medical circumstances.

This study was:

a.an observational study without any control group(s).

b.an experiment with control group(s).

c.an experiment without any control group(s).

d.an observational study with control group(s).

If the sample size in this study involved only 80 children instead of 241, but the percentage of children who's cough stopped was the same in all groups, then

a.the p-value would be smaller and results would definitely still be statistically significant.

b.the p-value would be bigger and the results may or may not still be significant.

c.the p-value would be smaller and the results may or may not still be significant.

d.the p-value would be bigger and the results would definitely still be significant.

In this situation:

a.the treatment was the explanatory variable and whether the child stopped coughing is the response variable.

b.the treatment was the response variable and whether the child stopped coughing is the explanatory variable

c.the medical circumstances affecting what is prescribed was the response variable and whether the child stopped coughing was the explanatory variable.

d.the medical circumstances affecting what is prescribed was the response variable and the treatment was the explanatory variable.

The standard error for the proportion of children taking levodropropizine who's cough stopped is about:

a.0.00025

b.0.47

c.0.05

d.0.18

14.Use the following information to answer the questions below:

Recently, the National Center for Education Statistics reported a study of a random sample of 1990 public school teachers whose first year teaching was in 2007-2008. The study found that 5 years later (in 2013) 17% of the teachers had left the profession. However, amongst the 1580 teachers who were assigned a mentor in their first year of teaching 14% had left the profession compared with 29% of the 410 teachers who did not have a mentor in their first year.

The standard error for the proportion of mentored teachers who left the profession before 2013 is:

a.14% (which equals .14 in decimal form)

b.5.6% (which equals .056 in decimal form)

c.2.5% (which equals .025 in decimal form)

d.0.9% (which equals .009 in decimal form)

The standard error for the proportion of un-mentored teachers who left the profession before 2013 is:

a.smaller than the previous answer

b.the same as the previous answer

c.larger than the previous answer

If the standard error of the difference between the proportions is 2.5% (0.025), what would be the 95% confidence interval for the difference between the proportions of mentored and un-mentored teachers who left the profession before 2013:

a.15% 1.3%

b.15% 2.5%

c.15% 8.3%

d.15% 5.0%

If the 95% confidence interval for the difference between the proportions of mentored and un-mentored teachers who left the profession before 2013 is (9%, 21%), what can be concluded?

a.The difference between the mentored and un-mentored teachers is significant.

b.The difference between the mentored and un-mentored teachers is not significant.

c.The difference between the mentored and un-mentored teachers shows that mentoring programs cause teachers to stay involved in teaching longer.

15.Use the following information to answer the questions below:

A paint manufacturer fills cans of paint using a machine that has been calibrated to fill the cans to contain an average of 1 gallon (128 ounces) each. To test whether their machine has come out of calibration and will tend to overfill the cans, the manufacturer takes a random sample of 100 cans and finds that they average 128.2 ounces with an standard deviation of 4 ounces. Is this strong evidence that the can-filling machine is set too high? We wish to carry out the appropriate hypothesis test.

In this situation the null hypothesis is that:

a.the long run average is greater than 128.2.

b.the long run average equals 128.2.

c.the long run average is greater than 128.

d.the long run average equals 128.

The p-value for the significance test is:

a.16%

b.2%

c.31%

d.68%

Suppose the p-value for the test is 0.21. We can then conclude

a.that the null hypothesis is a reasonable explanation of the data.

b.that the null hypothesis is a poor explanation of the data.

c.that the null hypothesis is true.

d.that the alternative hypotheses is true.

In this situation, the alternative hypothesis is

a.one-tailed

b.two-tailed

c.more than two-tailed