Question 1

Which of the following best describes an 'unstacked' data table format?

Accepted Answer

Each column represents a different group, and each row represents a value for that group.

Question 2

A researcher randomly assigns 100 patients to receive either a new medication or a placebo and measures their blood pressure weekly. What type of study is this?

Accepted Answer

Controlled experiment

Question 3

Which of the following variables is categorical?

Accepted Answer

Ethnicity

Question 4

A study finds that students who participate in sports are happier than those who do not. The study did not randomly assign students to participate in sports. What is the main limitation of this study?

Accepted Answer

It cannot establish causation due to lack of random assignment.

Question 5

When examining distributions of numerical data, which three components should you look for?

Accepted Answer

Shape, center, and spread

Question 6

Which of the following would most likely show a bimodal distribution?

Accepted Answer

The heights of all students in a high school separated by male vs. female

Question 7

Given a data set with a mean of $$37.9$$ and a standard deviation of $$9.2$$, what is the z-score for an age of $$45$$?

Accepted Answer

$$z = \frac{45 - 37.9}{9.2} = 0.77$$

Question 8

If a data set is strongly skewed to the right, which of the following is most likely true?

Accepted Answer

The mean number of friends is larger than the median.

Question 9

What is the interquartile range (IQR) for the following data: $$29, 33, 35, 37, 38, 40, 45$$?

Accepted Answer

$$IQR = 45 - 29 = 16$$

Question 10

A histogram of test scores for a group of students who received a 30-minute study session prior to taking a test is shown to be left-skewed. What does this suggest about the distribution of scores?

Accepted Answer

Most students scored high, with a few low scores.

Question 11

Given a data set with a mean of $$37.9$$ and a standard deviation of $$9.2$$, what age corresponds to a z-score of $$-2$$?

Accepted Answer

$$x = 37.9 + (-2)(9.2) = 19.5$$

Question 12

Which of the following best describes the median in a boxplot?

Accepted Answer

The line inside the box

Question 13

If the middle 50% of marathon finish times at the Olympics is from 136 to 144 minutes, what is the interquartile range (IQR)?

Accepted Answer

$$IQR = 144 - 136 = 8$$ minutes

Question 14

Which of the following is NOT a component of the shape of a distribution?

Accepted Answer

Center

Question 15

A boxplot shows the finish times for a marathon. If the median is less than the mean, what can you infer about the distribution?

Accepted Answer

The distribution is skewed to the right.

Question 16

Which of the following best describes a numerical variable?

Accepted Answer

A variable that can be measured and expressed with numbers, such as age or weight.

Question 17

If a data set is bimodal, what does this indicate about the data?

Accepted Answer

There are two distinct peaks or modes in the distribution.

Question 18

Which of the following is a correct interpretation of a z-score of $$0.77$$ for an age of $$45$$?

Accepted Answer

The age of $$45 is$$ $$0.77$$ standard deviations above the mean.

Question 19

Which of the following best describes the range of ages that would capture the middle $$50\% of $$the data for the set $$29, 33, 35, 37, 38, 40, 45$$?

Accepted Answer

Question 20

In a controlled experiment, what is the primary purpose of random selection?

Accepted Answer

To ensure that each participant has an equal chance of being assigned to any group, reducing bias.

Foundations of Descriptive Statistics: Data Types, Experimental Design, and Data Distributions

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