Exam 12: Introduction to Statistical Inference: Testing Hypotheses About Single Means Z and T
Exam 1: Introduction25 Questions
Exam 2: Frequency Distributions, Percentiles,34 Questions
Exam 3: Graphic Representation of Frequency Distributions25 Questions
Exam 4: Central Tendency25 Questions
Exam 5: Variability and Standard Z Scores37 Questions
Exam 6: Standard Scores and the Normal Curve27 Questions
Exam 7: Correlation38 Questions
Exam 8: Prediction40 Questions
Exam 9: Interpretive Aspects of Correlation and Regression23 Questions
Exam 10: Probability29 Questions
Exam 11: Random Sampling and Sampling Distributions24 Questions
Exam 12: Introduction to Statistical Inference: Testing Hypotheses About Single Means Z and T74 Questions
Exam 13: Interpreting the Results of Hypothesis Testing: Effect Size, Type I and Type II Errors, and Power42 Questions
Exam 14: Testing Hypotheses About the Difference Between Two Independent Groups33 Questions
Exam 15: Testing for a Difference18 Questions
Exam 16: Inference About Correlation Coefficients24 Questions
Exam 17: An Alternative to Hypothesis Testing: Confidence Intervals28 Questions
Exam 18: Testing for Differences Among Three or More Groups: One-Way Analysis of Variance and Some Alternatives49 Questions
Exam 19: Factorial Analysis of Variance30 Questions
Exam 20: Chi-Square and Inference About Frequencies27 Questions
Exam 21: Some Almost Assumption-Free Tests19 Questions
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For inference about single means, df is
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(Multiple Choice)
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Correct Answer:
D
The Director of Student Health Services wishes to know if her anti-smoking campaign has been effective. Last year, a complete survey of all students found the mean number of cigarettes smoked per day by students to be 8.6 with a standard deviation of 2.0. The Director of the Student Health Service obtains the following results from a recently selected random sample of students (in cigarettes smoked per day):
(a)Set up
and
(b)Perform the statistical test (
(c)Draw final conclusions.




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(Essay)
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Correct Answer:
(a)
< 8.6
(b)
reject
(c) Conclude that the campaign was effective in reducing smoking among students.
If
and
and the critical values of z are
when
and
when
what would we do if our calculated value of z were -2.80?






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(Multiple Choice)
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Correct Answer:
D
We conduct a two-tailed test at the .05 significance level with data that afford 8 degrees of freedom. When we look up the critical value of t, we will expect it to be ____________ the corresponding critical value of z.
(Multiple Choice)
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We are thinking of a two-tailed test, but decide on a one-tailed test. This means that
(Multiple Choice)
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As the number of degrees of freedom increases, student's distribution of t
(Multiple Choice)
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In general, "degrees of freedom" is most closely related to the
(Multiple Choice)
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When a one-tailed test is employed (rather than a two-tailed test),
(Multiple Choice)
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The answer to which of the following questions is the "key" to solving a statistical inference problem
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Glo-lite light bulbs are advertised as having an average life of 600 hours with a standard deviation of 20. Consumer's Advocates (CA) has received numerous complaints that the bulbs burn out much more quickly. In order to check on the validity of these complaints, CA tests a sample of 25 bulbs and obtains:
(a)Set up
and
(b)Perform the statistical test (
(c)Draw final conclusions.?(d)?Now repeat using






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Ms. Phillips, research director of a large city school district, wishes to compare the mean score on a widely used reading readiness test of entering first graders in her district with the national norm of 62 and a standard deviation of 8. The results for a random sample of 10 children from her district are:
(a) Set up
and
(b)Perform the statistical test (
(c)Draw final conclusions.
(d)Now repeat using






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If the outcome of a test is significant at the .05 level, it
(Multiple Choice)
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The new Streamer four-cylinder compact is advertised as obtaining 39.2 miles per gallon (estimated highway mileage). A competitor doubts their claim and tests a sample of Streamers under highway conditions with the following results (in m.p.g.): 35, 41, 36, 32, 40, 38, 38, 36. Do these results cast doubt on the advertised claim??
(a)Set up
and
(b) Determine the critical value(s) of
(c)Perform the statistical test.
(d)Draw final conclusions.



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Which, if any, need not be decided in advance of conducting the test of a null hypothesis?
(Multiple Choice)
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Compute the best estimates of
and
for each of the following samples:?
(a)pulse rate: 72, 86, 75, 66, 90;?
(b)number of tumors per rat: 2, 7, 8, 6, 6, 11, 3.


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