Question
DATA205 Introductory Analytics (QC)
Quiz 4: Chapters 7-8
Question 1A confidence level of 99% is the same as an alpha level of
a. 0.10
b. 0.001
c. 0.05
d. 0.01
Question 2A random sample of 500 reports an average yearly income of \$42,000 with a standard deviation of \$1000. An estimate of the parameter at the 95% level is about \$175 wide. In this research situation
a. the sample mean is \$175.
b. the sample size is much too small to justify the use of estimation procedures.
c. we can be 95% confident that the population mean is 42,000 ± 175.
d. the alpha level is 1000.
Question 3All other things being equal, larger sample will cost more to process
a. but will produce more precise intervals if the confidence level is low.
b. and will always produce wider confidence intervals.
c. but will not necessarily have narrower confidence intervals.
d. and will always produce narrower confidence intervals.
Question 4As our confidence in an interval estimate increases, the width of the interval
a. remains the same.
b. decreases.
c. increases or decreases depending on the alpha level.
d. increases.
Question 5As sample size increases, confidence interval width
a. increases.
b. changes proportionally.
c. decreases.
d. remains the same.
Question 6If you have a sample statistic and an unknown population standard deviation, you would use which formula to calculate the confidence interval.
a.
b. ?none of these choices are correct
c. ?
d. ?
Question 7In ________ of the cases, the mean of a sample selected by EPSEM will be more than ± 3 Z’s from the population mean.
a. less than 1%
b. more than 5%
c. more than 99%
d. more than 90%
Question 8In estimation procedures, ___________ are estimated based on the value of ____________.
a. sample, populations
b. parameters, statistics
c. statistics, parameters
d. values, frequencies
Question 9In estimation procedures, the Z score that corresponds to an alpha of .05 is

a. ± 1.96
b. ± 3.78
c. ± 2.58
d. ± 9.78
Question 10The average weight of a sample of women who attend aerobics classes at the YWCA is 130 pounds. We construct a confidence interval (using an alpha of 0.05) of ± 3.45. The upper and lower limits of our estimate are
a. 126.55 and 133.45.
b. 126.55 and 130.45.
c. unknown; these values will depend on the number of women who are truly serious about exercising.
d. 130.00 and 133.45.
Question 11The most commonly used confidence level is
a. 99.5%
b. 95%
c. 90%
d. 90.5%
Question 12The width of an interval estimate can be controlled by
a. changing the confidence level.
b. changing the alpha level.
c. changing the sample size.
d. Any of the above
Question 13A one-tailed test of significance could be used whenever
a. the researcher feels like it.
b. the researcher can predict a direction for the difference.
c. the null hypothesis is thought to be true.
d. the alpha level exceeds 0.10.

Question 14A sample of people attending a professional football game averages 13.7 years of formal education while the surrounding community averages 12.1. The difference is significant at the .05 level. What could we conclude?
a. The null hypothesis should be accepted.
b. The alpha level is too low.
c. The sample is significantly more educated than the community as a whole.
d. The research hypothesis should be rejected.
Question 15An alpha of 0.01 means that a decision to _______ the null hypothesis has a ___ in 100 chance of being
a. reject, 100
b. accept, 1
c. reject, 1
d. fail to reject, 1
Question 16Do sex education classes and free clinics that offer counseling for teenagers reduce the number of pregnancies among teenagers? The appropriate test of this hypothesis would be
a. cross-sectional.
b. a two-tailed test.
c. a one-tailed test.
d. participant observation.
Question 17If we reject a null hypothesis which is in fact true, we
a. have made a Type II error.
b. have made a correct decision.
c. have made a Type I error.
d. should have used a one-tailed test.
Question 18In hypothesis testing, the _____________ is the critical assumption, the assumption which is actually tested.
a. null hypothesis
b. assumption of a normal sampling distribution
c. research hypothesis
d. assumption that the sample was randomly selected
Question 19In most cases, a researcher sets out to?
a. ?disprove the research hypothesis.
b. ?prove the null hypothesis.
c. ?prove the research hypothesis.
d. ?disprove the null hypothesis.
Question 20In terms of hypothesis testing, “significance” refers to the?
a. ?difference between our observed and our predicted outcomes.
b. ?difference between an independent and dependent variable.
c. ?difference between the two independent variables.
d. ?difference between the sample and population values.
Question 21In tests of significance, if the test statistic does NOT fall in the critical region, we
a. reject the null hypothesis.
b. fail to reject the research hypothesis.
c. conclude that the population distribution is normal.
d. conclude that our alpha level was too low.
Question 22The null hypothesis in the one sample case is a statement of
a. no difference.
b. rejection.
c. acceptance.
d. agreement with the research hypothesis.
Question 23The probability of Type I error is
a. the alpha level.
b. .01
c. .05
d. beta.
Question 24The records of the state Division of Motor Vehicles reveals that 23% of all drivers have been ticketed at least once. Twenty five percent of a random sample of older drivers in the state have gotten at least one ticket. This difference has been tested and the researcher has failed to reject the null hypothesis. What can be concluded?
a. There is no significant difference between older drivers and drivers in general in terms of number of tickets.
b. Older drivers are worse drivers.
c. Older drivers are significantly different from drivers in general.
d. Older drivers are better drivers.
Question 25When testing for the significance of the difference between a sample mean and a population mean, degrees of freedom are equal to
a. 1 – alpha.
b. alpha.
c. N + 1
d. N – 1

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