Question 1

Which of the following best describes what a scatterplot is used for in statistics?

Accepted Answer

To visualize the relationship between two quantitative variables.

Question 2

A researcher collects data on the number of hours studied and exam scores for a group of students. Which variable should be considered the explanatory variable?

Accepted Answer

Number of hours studied

Question 3

Which of the following is NOT a feature to look for when interpreting a scatterplot?

Accepted Answer

Median

Question 4

Suppose a scatterplot shows a strong, positive, linear relationship between two variables. Which of the following is the most likely value for the correlation coefficient $$r$$?

Accepted Answer

$$r = 0.90$$

Question 5

Which of the following formulas correctly represents the correlation coefficient $$r$$?

Accepted Answer

$$r = \frac{\sum z_x z_y}{n-1}$$

Question 6

A timeplot is most useful for which type of data?

Accepted Answer

Data that is ordered over time

Question 7

Which of the following is a condition that must be checked before using correlation?

Accepted Answer

Quantitative Variables Condition

Question 8

If a scatterplot shows a strong curved pattern, but the correlation coefficient $$r is $$close to zero, what is the most likely explanation?

Accepted Answer

The relationship is not linear.

Question 9

What effect can an outlier have on the value of the correlation coefficient $$r$$?

Accepted Answer

All of the above.

Question 10

Which of the following statements is the best way to report a correlation found between two variables?

Accepted Answer

There is a strong association between the two variables.

Question 11

A study finds a strong positive correlation between ice cream sales and shark attacks. What is the most likely explanation for this result?

Accepted Answer

A lurking variable, such as temperature, affects both.

Question 12

Which of the following is true about the possible values of the correlation coefficient $$r$$?

Accepted Answer

$$-1 \leq r \leq 1$$

Question 13

A correlation coefficient $$r = 0.644 is $$calculated for the relationship between students’ heights and weights. How would you describe the strength of this association?

Accepted Answer

Moderate

Question 14

Which of the following best describes the purpose of a control chart in Statistical Process Control (SPC)?

Accepted Answer

To monitor variation in a process over time and identify out-of-control points.

Question 15

If the p-value for a correlation is less than 0.05, what is the correct interpretation?

Accepted Answer

There is statistically significant evidence of a linear association.

Question 16

Which of the following is a reason why correlation does not imply causation?

Accepted Answer

There may be a lurking variable affecting both variables.

Question 17

A timeplot of Kentucky Derby winning times shows a downward trend over many years. What does this indicate that a histogram of the same data would not?

Accepted Answer

There is a long-term trend in the data.

Question 18

Which of the following is the correct interpretation of a correlation coefficient $$r = -0.75$$?

Accepted Answer

There is a strong negative linear association.

Question 19

Which of the following is a correct step when you find outliers in your data before calculating correlation?

Accepted Answer

Investigate the cause of outliers before deciding what to do.

Question 20

Which of the following best describes the 'Straight Enough Condition' for correlation?

Accepted Answer

The relationship between variables should be approximately linear.

Scatterplots, Association, and Correlation: Study Notes for Introductory Statistics

Guida di studio - Domande di pratica

Study guide - Flashcard