Q: Which formula would you use to check if a value is an outlier using the interquartile range (IQR)?

Lower fence: $$Q_1 - 1.5$$ \times IQR$$, Upper fence: Q_3$ + 1.5 \times IQR$$

Question 1

Which of the following best describes the difference between a population and a sample in statistics?

Accepted Answer

A population includes all individuals of interest, while a sample is a subset of those individuals.

Question 2

Which formula correctly calculates the sample mean $$\bar{x}$$ for ungrouped data?

Accepted Answer

$$\bar{x} = \frac{\sum x_i}{n}$$

Question 3

A researcher wants to study the effect of a new drug. She randomly assigns patients to receive either the drug or a placebo and measures their recovery times. What type of study is this?

Accepted Answer

Designed experiment

Question 4

Which of the following is a measure of dispersion?

Accepted Answer

Standard deviation

Question 5

Given the following five-number summary for a data set: 10, 20, 30, 40, 50. What is the interquartile range (IQR)?

Accepted Answer

$$IQR = Q_3$ - Q_1$ = 40 - 20 = 20$$

Question 6

Which sampling method divides the population into groups and then randomly selects some of those groups to sample all individuals within them?

Accepted Answer

Cluster sampling

Question 7

A histogram is most appropriate for displaying which type of data?

Accepted Answer

Quantitative data

Question 8

If a distribution is skewed right, which measure of center is most likely to be greater than the others?

Accepted Answer

Mean

Question 9

Which formula is used to calculate the sample variance $$s^2$$ for ungrouped data?

Accepted Answer

$$s^2$$ = \frac{\sum (x_i - \bar{x}$$)^2$$}{n-1}$$

Question 10

A data value has a $$z-$$score of $$-2.5. $$What does this indicate about the value?

Accepted Answer

It is 2.5 standard deviations below the mean.

Question 11

According to the Empirical Rule, approximately what percentage of data falls within two standard deviations of the mean in a bell-shaped distribution?

Accepted Answer

95%

Question 12

Which of the following is a potential source of bias in survey sampling?

Accepted Answer

Nonresponse bias

Question 13

A researcher uses a survey where only people who feel strongly about the topic choose to respond. What type of bias is most likely present?

Accepted Answer

Voluntary response bias

Question 14

Which of the following best describes a lurking variable?

Accepted Answer

A variable not included in the study that affects the relationship between explanatory and response variables.

Question 15

Which of the following is NOT a characteristic of a completely randomized experiment?

Accepted Answer

Subjects are assigned to treatments based on their preferences.

Question 16

A boxplot is useful for identifying which of the following?

Accepted Answer

Outliers

Question 17

Which formula would you use to check if a value is an outlier using the interquartile range (IQR)?

Accepted Answer

Lower fence: $$Q_1 - 1.5$$ 	imes IQR$$, Upper fence: Q_3$ + 1.5 	imes IQR$$

Question 18

Which of the following best describes a variable that can take on any value within a given range?

Accepted Answer

Continuous quantitative variable

Question 19

In StatCrunch, which menu path would you use to construct a frequency distribution for qualitative data?

Accepted Answer

Stat \u003e Tables \u003e Frequency

Question 20

A data set has no value that occurs more than once. Which term best describes its mode?

Accepted Answer

No mode

Statistics Unit 1: Data Collection, Summarization, and Numerical Description

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