Quiz 12: Correlation Flashcards
A researcher studies the association between study motivation and grade. She finds that the Pearson’s correlation is statistically significant. Which of the following conclusions is definitely true?
A: The nonlinear correlation must be statistically significant
B: The magnitude of the relation must be large
C: The linear correlation must be statistically significant
C: The linear correlation must be statistically significant
A researcher gives 300 U.S. adults a survey and asks them to record their depression and anxiety levels. After analyzing the data, the researcher finds a statistically significant correlation between depression and anxiety. Can they conclude that depression causes anxiety?
A: Yes, they can conclude that depression causes anxiety.
B: No, but they can conclude that anxiety causes depression.
C: No, correlation does not necessarily imply causation.
C: No, correlation does not necessarily imply causation
For which pair of variables would Pearson’s correlation coefficient be the best statistic to calculate?
A: Group Membership (treatment group vs. control group) and Pain Level (on a scale from 0 to 100)
B: Marital Status (married, divorced, widowed, single) and Free Time (in hours per week)
C: Age (in years) and Height (in inches)
C: Age (in years) and Height (in inches)
A researcher studies the association between sleep hours per night and grade. She finds that the Pearson’s correlation is statistically significant and positive. What would be the most accurate description of the relationship between sleep hours and grade?
A: Sleeping more leads to better grades
B: Sleeping less leads to better grades
C: People who sleep less tend to have better grades
D: People who sleep more tend to have better grades
D: People who sleep more tend to have better grades
> You CANNOT say “leads.” “Leads” means “causes” and we can never say “causes.”
Which of the following numbers would indicate the strongest correlation?
A: -0.20
B: 0.76
C: 0.52
D: -0.91
D: -0.91
> Whether positive or negative, the larger number in Pearson’s correlation = a stronger correlation
Which of the following research scenarios would require a Pearson’s correlation test and does not allow a t-test?
A: An educational researcher studies the association between sex (male vs. female) and math ability
B: An educational researcher studies the association between GPA and time spent studying (using hour as the unit)
C: Juniors and seniors participate in a study motivation survey. These two groups’ motivation scores are compared.
B: An educational researcher studies the association between GPA and time spent studying (using hour as the unit)
> You can’t say “C” because it’s comparing two categorical groups’ scores vs. two numerical variables to one another
A researcher studies the association between study motivation and grade. She finds that the Pearson’s correlation is 0.9. Which of the following statements is correct?
A: The linear correlation must be statistically significant
B: The nonlinear correlation must be statistically significant
C: The magnitude of the relation is large
D: The grade can be predicted by study motivation with 90% accuracy
C: The magnitude of the relation is large
> We can’t use %
A psychologist is interested in exploring the association between the time spent playing video games and life satisfaction level. In his study, the probability value (p-value) is .01. Which of the following conclusions is true?
A: If the population correlation is truly nonzero, the probability of drawing a sample that gives a correlation as large as the one found in this study or more extreme is 0.01
B: The probability that the null hypothesis is true is .01
C: If the population correlation is truly zero (the null is true), the probability of drawing a sample that gives a correlation as large as the one found in this study or more extreme is 0.01
D: The probability that the population correlation is truly nonzero is .01
C: If the population correlation is truly zero (the null is true), the probability of drawing a sample that gives a correlation as large as the one found in this study or more extreme is 0.01
A researcher found that if human beings drink more cups of coffee, heart rate increases. Which of the following statements is true?
A: The correlation between the number of cups of coffee and heart rate is negative
B: The correlation between the number of cups of coffee and heart rate is positive
C: The correlation between the number of cups of coffee and heart rate is zero
B: The correlation between the number of cups of coffee and heart rate is positive
In which of the following scenarios can a researcher claim that the correlation between the number of cups of coffee and heart rate indicates a causal relationship?
A: The researcher asks participants to provide information about the number of cups of coffee they drink every day and records their heart rates.
B: The researcher requires participants to drink different numbers of cups of coffee. After 30 minutes, he records their hear rates.
B: The researcher requires participants to drink different numbers of cups of coffee. After 30 minutes, he records their hear rates.
If the Pearson’s correlation between two variables is 0, what can be said about the relationship between the two variables?
A: There is no relationship between the two variables
B: There is no linear relationship between the two variables
C: We cannot say anything about the relationship between the two variables for sure
B: There is no linear relationship between the two variables
You need to look at the image to answer this one:
A researcher recorded the number of friends and happiness level for five people they randomly sampled from the population. The values of these variables for the five subjects are given below:
If the fifth subject had instead had 18 friends and a happiness level of 5, how would this outlier have affected the Pearson’s correlation between number of friends and happiness level?
A: This outlier would decrease the Pearson’s correlation between number of friends and happiness level.
B: This outlier would increase the Pearson’s correlation between number of friends and happiness level.
C: This outlier would not change the Pearson’s correlation between number of friends and happiness level.
A: This outlier would decrease the Pearson’s correlation between number of friends and happiness level.
> You know that it will decrease it because all the happiness levels are super high and 5 is really low so it will pull the correlation way down
A researcher is interested in examining the relationship between the number of cigarettes someone smokes per day and the amount of years they live. The researcher obtains a Pearson’s correlation of -0.90. What does this indicate about the relationship between these variables?
A: As the number of cigarettes smoked by an individual per day increases, the amount of years they live increases.
B: The researcher must have made a mistake because Pearson’s correlation cannot be negative. It can only be a positive number from 0 to 1.
C: As the number of cigarettes smoked by an individual per day increases, the amount of years they live decreases.
C: As the number of cigarettes smoked by an individual per day increases, the amount of years they live decreases.
A researcher studying work pressure and job performance finds a Pearson’s correlation of 0. What can the researcher conclude based on this correlation value?
A: There is no relationship between these two variables at all.
B: There is definitely a nonlinear relationship between these two variables.
C: There isn’t a linear relationship between these two variables, but there could be a nonlinear relationship.
C: There isn’t a linear relationship between these two variables, but there could be a nonlinear relationship.
