Correlation between coffee and cholesterol
1. A study from a Colombian research center is about to publish a pilot study regarding a new coffee plant that they believe can reduce total cholesterol in humans. They gave increasing doses (cups of coffee) to a test patient over several weeks and recorded the following data:
caffeine (mg) Cholesterol level (mg/dL)
100 684
200 547
300 200
400 399
500 415
600 400
700 58
Evaluate the claim that the caffeine from this new plant reduces cholesterol by plotting caffeine levels (x) versus the cholesterol levels (y).
a. What is the correlation coefficient r and what does it mean in this case?
b. What is the coefficient of determination and what does it mean in this case?
c. Is there a statistically significant correlation between caffeine intake and cholesterol levels in this case?
Q2 Regression-How much coffee do I have to drink?
Given the data presented in Discussion Question 1 for this week, determine how much coffee you must drink to lower your total cholesterol to 150 mg/dL. To get the answer, plot a regression line in StatCrunch and discuss how to do the following:
a) What is the intercept? (or -what would be your cholesterol level while ingesting no caffeine?)
b) What is the slope? (or, what is what we call b in the linear regression equation?)
c) How many cups of coffee must you drink to lower your total cholesterol to 150 mg/dL (given that 1 cup of coffee equals 100 mg of caffeine)?