More cereal: An analysis of the amount if fiber in grams and the potassium con-

ID: 3370078 • Letter: M

Question

tent (in milligrams) in servings of 77 breakfast cereals produced the regression

model Potassium= 38 + 27Fiber

1. In this context what does it mean to say that the cereal has a negative

residual?

2. Explain what the slope means.

3. The correlation between a cereal's fiber content and potassium content is

r= 0.903. what fraction of variability in potassium is accounted for by the

amount of fiber that serving contains?

1. In this context, the cereal has a negative residual means we have underestimated Potassium while regressing on Fiber.

2. For a unit increase in amount of Fiber, amount of Potassium increases 27 units.

3. Here R2 = 0.9032 = 0.815409

So, 81.4509% of variability in potassium is accounted for by the amount of fiber that serving contains.

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