Psych 100A - Quiz 12 Correlation

Which of the following numbers would indicate the strongest correlation?

-0.91

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?

As the number of cigarettes smoked by an individual per day increases, the amount of years they live decreases.

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?

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 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?

People who sleep more tend to have better grades

A researcher found that if human beings drink more cups of coffee, heart rate increases. Which of the following statements is true?

The correlation between the number of cups of coffee and heart rate is positive

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?

The linear correlation must be statistically significant

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?

The magnitude of the relation is large

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?

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?

There is no linear relationship between the two variables

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?

There isn't a linear relationship between these two variables, but there could be a nonlinear relationship.

For which pair of variables would Pearson's correlation coefficient be the best statistic to calculate?

Age (in years) and Height (in inches)

Which of the following research scenarios would require a Pearson's correlation test and does not allow a t-test?

An educational researcher studies the association between GPA and time spent studying (using hour as the unit)

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?

No, correlation does not necessarily imply causation.

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:

This outlier would decrease the Pearson's correlation between number of friends and happiness level.