Question

A researcher conducted a study looking at hours of screen time, and its relationship to a student’s amount of REM sleep at night. Results indicated a correlation, and that as hours of screen time increased, minutes of REM sleep decreased. If the correlation was - .78, use the Cohen’s table of effect size magnitudes Figure 14.2: Strength guidelines for correlation coefficients for the social sciences) to indicate the strength of the correlation, and indicate if it is a positive correlation or a negative correlation.

Answer 1

Correlation coefficient tells us about the strength and direction of relationship between two variables

In the question, it is given that the correlation coefficient is r = -0.78

Negative sign in this correlation coefficient tells us that there is negative or inverse relationship between the two variables

Magnitude of correlation coefficient is 0.78, which is greater than 0.70. So, the magnitude is strong.

Therefore, we can say that there is strong negative correlation between the two variables