Question

2. An educational psychologist gathers data from a sample of college students. He finds the correlation between grade point average and class attendance to be 0.60, and he finds the correlation between grade point average and amount of time spent playing video games to be -0.60. What can the educational psychologist conclude about these correlations?

- The correlation of r = 0.60 is stronger than the correlation of r = -0.60.
- The correlation of r = 0.60 is just as strong as the correlation of r = -0.60.
- The correlation of r = 0.60 is weaker than the correlation of r = -0.60.
- We cannot know which correlation is stronger without knowing the size of the sample.

3. A researcher wants to study how the Weight (in pounds) of a Greyhound dog relates to its Top Speed (in miles per hour). We take a small sample of greyhounds, and produce the following regression equation to help explain the relationship between these two variables:

Predicted Top Speed = 33.75 + 0.125*(Weight)

Which of the following is a correct interpretation of the slope of this regression equation?

- As a greyhound's Top Speed goes up by 1 mile per hour, we predict that its Weight will increase by 0.125 pounds.
- As a greyhound's Top Speed goes up by 1 mile per hour, we predict that its Weight will increase by 33.75 pounds.
- As a greyhound's Weight goes up by 1 pound, we predict that its Top Speed will go up by 0.125 miles per hour.

As a greyhound's Weight goes up by 1 pound, we predict that its Top Speed will go up by 33.75 miles per hour

7. If a data point falls above the regression line, its residual will be _______.

- less than 0.
- equal to 0.
- greater than 0.
- unknown.

.

Answer #1

2. Strength of correlation is by value of r and not by it sign

So answer here is

- The correlation of r = 0.60 is just as strong as the correlation of r = -0.60.

3. Here Top Speed = 33.75 + 0.125*(Weight)

So Slope is 0.125, which means for a increase in weight speed will change by 0.125

So answer here is

C. As a greyhound's Weight goes up by 1 pound, we predict that its Top Speed will go up by 0.125 miles per hour.

7.If data point falls above the regression line, residual will be positive

So answer here is

C. greater than 0.

A random sample of 15 weeks of sales (measured in $) and 15
weeks of advertising expenses (measured in $) was taken and the
sample correlation coefficient was found to be r = 0.80. Based on
this sample correlation coefficient we could state
That the percentage of the variation in sales that is shared
with the variation in advertising is about 80%.
That the percentage of the variation in sales that is shared
with the variation in advertising is about...

1. For a pair of sample x- and y-values, what is the difference
between the observed value of y and the predicted value of y? a) An
outlier b) The explanatory variable c) A residual d) The response
variable
2. Which of the following statements is false:
a) The correlation coefficient is unitless. b) A correlation
coefficient of 0.62 suggests a stronger correlation than a
correlation coefficient of -0.82. c) The correlation coefficient,
r, is always between -1 and 1....

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