Regression Analysis Review

Which statement correctly describes the association between hot chocolate sales and ice cream sales?

• There is a negative association because in general, as hot chocolate sales increase, ice cream sales decrease.

• There is a negative association because in general, as hot chocolate sales increase, ice cream sales increase.

• There is a positive association because in general, as hot chocolate sales increase, ice cream sales decrease.

• There is a positive association because in general, as hot chocolate sales increase, ice cream sales increase.

You find a line of fit for a set of data and calculate that the correlation coefficient for the model is –0.34. Which statement best describes the fit of the model to the data?

• The correlation coefficient suggests a strong positive correlation, so this model is a good fit for the data.

• The correlation coefficient suggests a weak positive correlation, so this model is not a good fit for the data.

• The correlation coefficient suggests a weak negative correlation, so this model is not a good fit for the data.

• The correlation coefficient suggests a strong negative correlation, so this model is a good fit for the data.

Find the approximate correlation coefficient for a linear model for the data.

• 0.92

• 0

• -0.92

• -1

The table shows the relationship between weight and lifespan for several dog breeds. Find an equation of the line of best fit and the correlation coefficient. How well does the line represent the data?

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• 
• 
• 

How would the removal of point A from the scatterplot and its LSRL below affect the correlation coefficient?

• The correlation coefficient would become stronger.

• The correlation coefficient would become weaker.

• The correlation coefficient would remain approximately the same.

• It is impossible to determine the effect of the point on the correlation coefficient.

Consider the following three scatterplots. All three scatterplots are drawn to the same scale on both the x and y axes. Which of the following correctly orders these from smallest to largest based on the value of the correlation coefficient?

• I, II, III

• II, III, I

• III, II, I

• II, I, III

A study was carried out to investigate the relationship between x = time spent working each week (hours) and y = time spent on math homework on a typical weekend (in minutes) for a random sample of 20 students in a first-quarter calculus course. When the simple linear regression model is fit to the sample data, which point will have the smallest (in magnitude) residual?

• A

• B

• C

• A,B,C,D have the same positive value

If removing an observation from a data set would have a marked change on the equation of the

least-squares regression line, the point is called

• resistant

• a residual

• influential

• a response

A study is conducted to determine if one can predict the yield of a crop based on the amount of fertilizer applied to the soil. What is the response variable?

• yield of the crop

• amount of fertilizer applied

• the experimenter

• amount of rainfall

Suppose a study finds that the correlation coefficient relating job satisfaction to salary is r = 1. Which of the

following are proper conclusions?

I. High salary causes high job satisfaction.

II. Low salary causes low job satisfaction.

III. There is a very strong association between salary and job satisfaction.

• I only

• II only

• III only

• I and II