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Explain briefly why each of the three conditions—Random, Normal, and Independent—is important when constructing a confidence interval.

Short Answer

Expert verified

Random: It is necessary if we want to generalize the conclusions to the entire population.

Normal: A necessary condition for the construction of the confidence interval.

Independent: Required for the computation of the standard deviation.

Step by step solution

01

Concept Introduction

The probability that a population parameter will fall between a set of values for a particular proportion of the time is referred to as a confidence interval.

02

Explanation

Random: This is required if we wish to apply the findings to the entire population.

Normal: This is a crucial requirement for constructing the confidence interval; if the distribution is not normal, a different approach must be used, as this method may produce inaccurate findings.

Because dependent data might lead to erroneous conclusions, independent data is required for standard deviation computation.

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Most popular questions from this chapter

61. Willows in Yellowstone Writers in some fields summarize data by giving x¯and its standard error rather than x¯and sx. Biologists studying willow trees in Yellowstone National Park reported their results in a table with columns labeled x¯+SE. The table entry for the heights of willow trees (in centimeters) in one region of the park was 61.55±19.03.The researchers measured a total of23 trees.
(a) Find the sample standard deviation sx for these measurements. Show your work.
(b) Explain why the given interval is not a confidence interval for the mean height of willow trees in this region of the park.

You want to compute a 90%confidence interval for the mean of a population with unknown population standard deviation. The sample size is 30. The value of role="math" localid="1649226392559" tyou would use for this interval is

(a)1.645(b).1.699(c)1.697

(d) 1.96(e) 2.045

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(a) Construct and interpret a 95%confidence interval for p. Follow the four-step process.

(b) Is it plausible that the true proportion of American teens with profiles who have posted photos of themselves is 0.75? Use your result from part (a) to support your answer.

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These results are based on telephone interviews with a randomly selected national sample of 1028teenagers in the Gallup Poll Panel of households, aged 13to 17. For results based on this sample, one can say . . . that the maximum error attributable to sampling and other random effects is ±3percentage points. In addition to sampling error, question-wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.16

(a) We omitted the confidence level from the footnote. Use what you have learned to determine the confidence level, assuming that Gallup took an SRS.

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Plant managers are concerned that the number of accidents may be significantly higher during the midnight to8:00a.m. shift than during the 4:00p.m. to midnight shift. What would you tell them? Give appropriate statistical evidence to support your conclusion.

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