Q: Which formula is used to check for outliers using the interquartile range (IQR)?

$$\text{Lower fence} = Q_1$ - 1.5 \times IQR$$ and $$\text{Upper fence} = Q_3$ + 1.5 \times IQR$$

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 of the following is a parameter, not a statistic?

Accepted Answer

The average height of all students in a university.

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 compares outcomes. What type of study is this?

Accepted Answer

Designed experiment

Question 4

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

Accepted Answer

Cluster sampling

Question 5

Which of the following is an example of a lurking variable?

Accepted Answer

A variable not measured in a study that influences both the explanatory and response variables.

Question 6

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

Accepted Answer

Quantitative data

Question 7

Given the following data set: 2, 4, 7, 10, 12. What is the median?

Accepted Answer

7

Question 8

Which formula correctly calculates the sample variance for ungrouped data?

Accepted Answer

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

Question 9

A distribution is described as 'skewed right.' Which of the following best describes its shape?

Accepted Answer

The right tail is longer than the left tail.

Question 10

Which of the following is a resistant measure of center?

Accepted Answer

Median

Question 11

A researcher collects data on the number of hours students study per week and their exam scores. Which variable is most likely the explanatory variable?

Accepted Answer

Number of hours studied

Question 12

Which of the following best describes the Empirical Rule for a bell-shaped distribution?

Accepted Answer

About 68% of data within 1 standard deviation, 95% within 2, and 99.7% within 3 standard deviations of the mean.

Question 13

If a data value has a z-score of $$z = 2.5$$, what does this indicate?

Accepted Answer

The value is 2.5 standard deviations above the mean.

Question 14

Which of the following is NOT a source of bias in sampling?

Accepted Answer

Random assignment

Question 15

A five-number summary includes which of the following values?

Accepted Answer

Minimum, Q1, Median, Q3, Maximum

Question 16

Which formula is used to check for outliers using the interquartile range (IQR)?

Accepted Answer

$$	ext{Lower fence} = Q_1$ - 1.5 	imes IQR$$ and $$	ext{Upper fence} = Q_3$ + 1.5 	imes IQR$$

Question 17

A survey asks, 'How satisfied are you with your internet service?' and provides a scale from 1 (not satisfied) to 5 (very satisfied). What type of variable is this?

Accepted Answer

Qualitative (ordinal)

Question 18

Which StatCrunch menu path would you use to construct a frequency distribution for qualitative data?

Accepted Answer

Stat \u003e Tables \u003e Frequency

Question 19

If the range of a data set is 20 and the smallest value is 15, what is the largest value?

Accepted Answer

35

Question 20

Which of the following best describes a scenario where the placebo effect might occur?

Accepted Answer

A patient reports improvement after receiving a sugar pill, believing it is real medication.

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

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