The p-value for a statistical test represents (choose the best answer)

a. The probability that the alternative hypothesis is likely to be true

b. The probability that the test statistic is from a z-score distribution

c. The probability of obtaining the test statistic when the null hypothesis is true

d. The probability that the test statistic is from the alternative hypothesis distribution

 A researcher conducts a well-designed study to compare a sample mean to a known population mean and finds a z-test of 1.98, p-value=.048, alpha=.05, two-tailed. What should she conclude?

a. The 95% confidence interval of the z-statistic will contain zero

b. The conclusion cannot be made without knowing the direction of the alternative hypothesis

c. Data support the alternative hypothesis

d. She fails to reject the null hypothesis

 A researcher wants to test if the rate of smoking among adults in Chicago is greater than the national rate of 18%. A random sample of 225 adults revealed 15% were current smokers. Calculate the appropriate test statistic

a. z=-1.17

b. t=.078 with 1 degree of freedom

c. z=1.26

d. z=-3.06

 A researcher wants to know if babies born to mothers exposed to second hand smoke are smaller than the average for the general population, known to be 3389 grams. A random sample of 400 medical records was selected from pregnant non-smoking women exposed to second hand smoke. The average birth weight of babies from this sample was 3280 with a standard deviation of 730. What is the known from this description?

a. The z-test statistic will be positive

b. The t-test statistic will be negative

c. A sample size of 100 would be adequate to test this hypothesis

d. All infants born to the sample of women were smaller than the general population average

A researcher is interested in knowing if the rate vitamin D deficiency differs for patients with a rare cancer compared to the general population. Approximately 42% of the US population has a vitamin D deficiency. The researcher uses a nation-wide database and finds only 30 living patients with this cancer. The hypotheses are H0: p=.42, Ha: p?.42, alpha=.05 and they fail to reject the null. Which of the following is true?

a. A type I error is likely with this sample size

b. Using a one-tailed test and alpha=.10 would reduce the probability of a type II error

c. The sample is too small to use the z-test for a population proportion, the condition was not met

d. We must know the sample mean to tell if the test conditions for the test were met

 A researcher believes that college freshmen are exercising less than the recommended guidelines of 150 minutes per week. His hypotheses are H0: ?=150, Ha: ?<150, alpha=.05. He surveys a random sample of 4000 college freshman and obtains a mean of 149.65 minutes per week with p-value=.023. Select the best answer.

a. The one tailed test was more conservative for detecting a significant difference.

b. The results would not be significant if alpha=.05, two-tailed

c. A type II error may have occurred

d. The difference, though statistically significant, is not compelling or practically meaningful

You conducted a study and believe your statistical conclusion may be a type I error. What will you do differently in your next study to reduce the probability of making a type I error?

a. Use alpha=.01

b. Use a larger sample size

c. Use a one-tailed test

d. all of the above

 A study is testing whether siblings differ in their hours of television viewing based on gender. A sample of 45 families with one son and one daughter are enrolled. What test statistic should be used?

a. Regression for inference

b. Matched pairs t-test

c. Independent samples t-test

d. Chi-squared statistic