Question
DATA205 Introductory Analytics (QC)
Quiz 4: Chapters 7-8
Question 1A confidence level of 99% is the same as an alpha
level of
Answers:
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
Answers:
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
Answers:
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
Answers:
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
Answers:
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.
Answers:
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.
Answers:
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 ____________.
Answers:
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
Answers:
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
Answers:
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
Answers:
a. 99.5%
b. 95%
c. 90%
d. 90.5%
Question 12The width of an interval estimate can be
controlled by
Answers:
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
Answers:
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?
Answers:
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
Answers:
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
Answers:
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
Answers:
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.
Answers:
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?
Answers:
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?
Answers:
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
Answers:
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
Answers:
a. no difference.
b. rejection.
c. acceptance.
d. agreement with the research hypothesis.
Question 23The probability of Type I error is
Answers:
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?
Answers:
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
Answers:
a. 1 – alpha.
b. alpha.
c. N + 1
d. N – 1
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