Introduction to Confidence Intervals: The Basics

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Questions 1-2

Question 1.

True or false: The sample statistic usually differs from the population parameter because of bias.

False

True

Incorrect. The sample statistic usually differs from the population parameter because of sampling variability.

Correct. The sample statistic usually differs from the population parameter because of sampling variability.

Incorrect. Try again.

Question 2.

What provides us information for predicting the expected maximum difference between the sample statistic, $\overline{x}$ , and the population parameter, µ?

The population distribution

The distribution of data in a sample

The sampling distribution of

$\overline{x}$

Incorrect. The sampling distribution of

$\overline{x}$ provides us probabilities on

$\overline{x}$ and a measure of the variability of

$\overline{x}$ with the standard deviation of the sampling distribution of

$\overline{x}$ .

Correct. The sampling distribution of

$\overline{x}$ provides us probabilities on

$\overline{x}$ and a measure of the variability of

$\overline{x}$ with the standard deviation of the sampling distribution of

$\overline{x}$ .

Incorrect. Try again.

Question 3

110

Question 3.

According to these results, what is the estimated maximum error?

2.9%

50%

33%

95%

Incorrect. Margin of error is an estimate of the maximum size of the error.

Correct. Margin of error is an estimate of the maximum size of the error.

Incorrect. Try again.

Questions 4-5

145

Question 4.

What is used to estimate the value of a parameter?

A confidence interval

A test of significance

Incorrect. A confidence interval is used to estimate the value of a parameter.

Correct. A confidence interval is used to estimate the value of a parameter.

Incorrect. Try again.

Question 6

208

Question 6.

True or false: Some inferential procedures have conditions that must be, but others do not.

False

True

Incorrect. All statistical inferential procedures have conditions that must be met for the results to be valid.

Correct. All statistical inferential procedures have conditions that must be met for the results to be valid.

Incorrect. Try again.

Question 7

280

Question 7.

Which one of the following is NOT a simple condition for inference on µ?

The distribution of the response variable is Normal.

The value of σ is known.

The value of µ is known.

The data are collected using an SRS.

Incorrect. Since we are doing inference on µ, we do not need to know the value of µ.

Correct. Since we are doing inference on µ, we do not need to know the value of µ.

Incorrect. Try again.

Question 8

316

Question 8.

True or false: All inferential procedures always require properly collected data for the results to be valid.

False

True

Incorrect. This is the most important requirement for valid statistical inference.

Correct. This is the most important requirement for valid statistical inference.

Incorrect. Try again.

Question 9

353

Question 9.

Why should we always plot our data before performing an inferential procedure?

To check for outliers which negate Normality.

To measure the variability of the data.

To obtain an estimate of the parameter.

Incorrect. Since outliers are problematic and negate Normality, we always plot our data and check for outliers.

Correct. Since outliers are problematic and negate Normality, we always plot our data and check for outliers.

Incorrect. Try again.

Question 10

388

Question 10.

True or false: In practice, since we seldom know the value of σ, we use s to estimate σ.

False

True

Incorrect. In practice, we rarely know the value of σ (the population standard deviation) when we want to estimate the value of µ. So we use s (the sample standard deviation) to estimate σ.

Correct. In practice, we rarely know the value of σ (the population standard deviation) when we want to estimate the value of µ. So we use s (the sample standard deviation) to estimate σ.

Incorrect. Try again.

StatTutor Lesson - Introduction to Confidence Intervals: The Basics

Questions 1-2

Question 1.

Question 2.

Question 3

Question 3.

Questions 4-5

Question 4.

Question 5.

Question 6

Question 6.

Question 7

Question 7.

Question 8

Question 8.

Question 9

Question 9.

Question 10

Question 10.