Week Four, Discussion One
Q1 Correlation between coffee and cholesterol
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).
- What is the correlation coefficient r and what does it mean in this case?
- What is the coefficient of determination and what does it mean in this case?
- Is there a statistically significant correlation between caffeine intake and cholesterol levels in this case?
Week Four, Discussion Two
Q2 Regression- What is the predicted cholesterol level?
Given the data presented in Discussion Question 1 for this week, determine the cholesterol level of someone who drank two and a half cups of coffee a day. To get the answer, plot a regression line in StatCrunch and post your answers from StatCrunch for 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) What is the cholesterol level of someone who drank two and a half cups of coffee a day (given that 1 cup of coffee equals 100 mg of caffeine)?