Question 1

Which of the following best describes the difference between a statistic and a parameter?

Accepted Answer

A statistic is a numerical summary of a sample, while a parameter is a numerical summary of a population.

Question 2

A researcher wants to study the effect of a new drug on blood pressure. She randomly assigns participants to either receive the drug or a placebo and measures their blood pressure after 6 weeks. What type of study is this?

Accepted Answer

Experiment

Question 3

Which of the following variables is both quantitative and continuous?

Accepted Answer

Temperature measured in degrees Celsius

Question 4

A survey asks respondents to rate their satisfaction with a service as 'Unsatisfied', 'Neutral', or 'Satisfied'. What level of measurement is this?

Accepted Answer

Ordinal

Question 5

Which sampling method involves dividing the population into groups based on a characteristic, then randomly sampling from each group?

Accepted Answer

Stratified sampling

Question 6

A histogram of exam scores shows most scores clustered to the left with a long tail to the right. How would you describe the shape of this distribution?

Accepted Answer

Right-skewed

Question 7

If a sample has the following values: 2, 4, 4, 6, 8, what is the mean?

Accepted Answer

$$\frac{2+4+4+6+8}{5} = 4.8$$

Question 8

Which of the following statistics is considered resistant to extreme values?

Accepted Answer

Median

Question 9

Given a sample of 5 values: 10, 12, 14, 16, 18, what is the sample variance?

Accepted Answer

$$\frac{(10-14)^2$ + (12-14)^2$ + (14-14)^2$ + (16-14)^2$ + (18-14)^2$}{4} = 10$$

Question 10

A student scored 85 on a test where the mean was 80 and the standard deviation was 5. What is the student's z-score?

Accepted Answer

$$z = \frac{85-80}{5} = 1$$

Question 11

If a boxplot shows the median closer to the lower quartile and the upper whisker is much longer than the lower whisker, what can you infer about the distribution?

Accepted Answer

The distribution is right-skewed.

Question 12

Which of the following best describes response bias?

Accepted Answer

It occurs when participants provide inaccurate answers due to wording or interviewer influence.

Question 13

A time-series graph shows the number of flu cases each month for two years. What type of variable is being measured?

Accepted Answer

Quantitative, discrete

Question 14

If the empirical rule applies, what percentage of data falls within two standard deviations of the mean in a bell-shaped distribution?

Accepted Answer

Approximately 95%

Question 15

A regression equation is $$y = 2x + 5. If$$ $$x = 3$$, what is the predicted value of $$y$$?

Accepted Answer

$$y = 2 	imes 3 + 5 = 11$$

Question 16

Which of the following statements about correlation is correct?

Accepted Answer

Correlation measures the strength and direction of a linear relationship between two variables.

Question 17

In a contingency table showing gender (male/female) and preference for a new product (like/dislike), what is a marginal distribution?

Accepted Answer

The distribution of gender regardless of product preference.

Question 18

A residual in regression analysis is defined as:

Accepted Answer

The actual value minus the predicted value.

Question 19

Which of the following is an example of a confounding variable in a study examining the relationship between exercise and weight loss?

Accepted Answer

The amount of water consumed by participants.

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