Question

1. Sampling error is evident when:

a. a question is poorly worded and results in bias

b. the sample is too small

c. the sample is not random

d. the sample mean differs from the population mean

2. Using an alpha = 0.05 a confidence interval for a population mean is determined to be 3.65 to 3.75. If the level of significance is decreased, the interval for the population mean:

a. becomes narrower

b. becomes wider

c. does not change

d. increases or decreases depending on the value of the population mean

3. The Z value associated with a two-sided 82% confidence interval is

a. 1.41

b. 1.34

c. 0.46

d. 1.75

Answer 1

1) Sampling mean is the difference between the sample statistic and the population parameter of interest. If the sample statistic is the sample mean , then sampling error is the difference between the sample mean and the unknown population mean. Sampling error is evident when :

d. the sample mean differs from the population mean

2)  Using an alpha = 0.05 a confidence interval for a population mean is determined to be 3.65 to 3.75. Now, we know that decreasing the significance level means increasing the confidence level. When we increase the confidence level, the width of the interval also increases. Therefore, the correct answer is:

b. becomes wider

3) We find the z critical value for 82% confidence level from the z critical values table. From the critical values table, the z critical value is 1.34.

b. 1.34