Imagine that you are interested in whether there is a relationship between the amount of coffee people drink and the number of hours they sleep each night. Determine whether you expect a positive or a negative relationship between the cups of coffee people drink and the number of hours they sleep.
• Ask 12 friends or family members how many cups (approximately 8 oz.) of coffee they drink each day and how many hours they sleep each night. Create a table that includes each participant, a column for cups of coffee, and a column for sleep that looks something like this:
Participant Cups of Coffee (X) Hours of Sleep (Y)
Erik 4 7
Joe 3 8
Ted 1 6
Jose 3 9
Victor 3 5
Claire 0 7
Suzanne 2 9
Jorge 4 8
Dan 6 6
Jayeoon 2 12
Hwangjin 4 4
Erika 2 9
• Create a scatter diagram using Figure 10.1 as a guide. Draw a line through the scatter diagram.
Post the list of scores for your participants. Then respond briefly to each of the following questions about your findings:
• What does your scatter diagram look like? Briefly describe it.
The data points are relatively concentrated together with a few vertical outliers. The intercept was 8.265, and the coefficient for coffee was -.3976.
• Based on your prediction about the relationship between the amount of coffee people drink and the number of hours they sleep, what is your H0 and what is your HA ?
My prediction is correct- they had a negative relationship as the coefficient for coffee is a negative.
• Did you find a positive linear relationship or a negative linear relationship? How do you know?
Weak negative relationship- the correlation coefficient is -.30.
• If you were pursuing this study, what calculations would you perform to describe this relationship and why?
Correlation coefficient- to understand correlation between variables
Bivariate Regression- it would help to understand what the average cup of coffee does to total sleeping time
• Without completing the calculations, assume that you obtained a significant result. What would you conclude?
I would conclude that drinking coffee is correlated with fewer hours of sleep.