© 2013 Pearson Education, Inc. Active Learning Lecture Slides For use with Classroom Response Systems Introductory Statistics: Exploring the World through Data, 1e by Gould and Ryan Chapter 4: Regression Analysis: Exploring Associations between Variables Slide 4 - 1

True or False In a scatterplot, each point represents one observation. A. True B. False Slide ? - 2 © 2013 Pearson Education, Inc.

When studying scatterplots, we look for A. trend B. strength C. shape D. all of the above Slide ? - 3 © 2013 Pearson Education, Inc.

Which of the following depicts a positive association? Slide ? - 4 © 2013 Pearson Education, Inc. A.B. C. D.

Which of the following depicts no trend? Slide ? - 5 © 2013 Pearson Education, Inc. A. B. C. D.

Which of the following depicts a changing trend? Slide ? - 6 © 2013 Pearson Education, Inc. A. B. C. D.

Which of the following depicts a negative association? Slide ? - 7 © 2013 Pearson Education, Inc. A. B. C. D.

True or False Weak associations result in a large amount of scatter in the scatterplot. A. True B. False Slide ? - 8 © 2013 Pearson Education, Inc.

True or False A large amount of scatter means that points have a only a little spread in the vertical direction. A. True B. False Slide ? - 9 © 2013 Pearson Education, Inc.

Which of the following depicts a stronger association? Slide ? - 10 © 2013 Pearson Education, Inc. A. B.

True or False The simplest shape for a trend is linear. A. True B. False Slide ? - 11 © 2013 Pearson Education, Inc.

Which of the following depicts a linear trend? Slide ? - 12 © 2013 Pearson Education, Inc. A. B.

True or False The correlation coefficient is a number that measures the strength of the linear association between two numerical variables. A. True B. False Slide ? - 13 © 2013 Pearson Education, Inc.

Which of the following depicts the strongest positive correlation? Slide ? - 14 © 2013 Pearson Education, Inc. A. B. C.D.

Which of the following depicts the strongest negative correlation? Slide ? - 15 © 2013 Pearson Education, Inc. A. B. C. D.

Which of the following depicts a perfectly linear, positive correlation? Slide ? - 16 © 2013 Pearson Education, Inc. A. B. C. D.

Which of the following depicts a perfectly linear, negative correlation? Slide ? - 17 © 2013 Pearson Education, Inc. A. B. C. D.

Which of the following depicts no correlation? Slide ? - 18 © 2013 Pearson Education, Inc. A. B. C. D.

A positive correlation between the number of blankets sold in Canada per week and the number of brush fires in Australia per week means that A. Cold Canadians cause Australian brush fires. B. Selling blankets in Canada causes brush fires in Australia. C. Brush fires in Australia cause Canadians to buy blankets. D. None of the above. Slide ? - 19 © 2013 Pearson Education, Inc.

What can we conclude from the fact that the number of liquor stores in a neighborhood is positively correlated with the crime rate in that neighborhood? A. Closing liquor stores will decrease crime. B. More liquor stores causes more crime. C. Adding a liquor store will increase crime. D. Neighborhoods with higher-than-average number of liquor stores typically (but not always) have a higher-than- average crime rate. Slide ? - 20 © 2013 Pearson Education, Inc.

True or False No matter how tempting, do not conclude that a cause-and-effect relationship between two variables exists just because there is a correlation, no matter how close to +1 or –1 that correlation might be ! A. True B. False Slide ? - 21 © 2013 Pearson Education, Inc.

To find the correlation coefficient, A. Add the products of the z-scores and divide by n – 1. B. Use the formula C. Both of the above D. None of the above. Slide ? - 22 © 2013 Pearson Education, Inc.

True or False When computing r, changing the order of variables does not change r. A. True B. False Slide ? - 23 © 2013 Pearson Education, Inc.

True or False When computing r, adding or multiplying each observation by a constant does not affect r. A. True B. False Slide ? - 24 © 2013 Pearson Education, Inc.

True or False The correlation coefficient must have has units. A. True B. False Slide ? - 25 © 2013 Pearson Education, Inc.

True or False The correlation can be misleading when you do not have a linear relationship. A. True B. False Slide ? - 26 © 2013 Pearson Education, Inc.

True or False The correlation coefficient does not tell you whether an association is linear. However, if you already know that the association is linear, then the correlation coefficient tells you how strong the association is. A. True B. False Slide ? - 27 © 2013 Pearson Education, Inc.

True or False The regression line is a tool for making predictions about future observed values. A. True B. False Slide ? - 28 © 2013 Pearson Education, Inc.

In the regression equation y = a + bx, A. The letter a represents the intercept. B. The letter b represents the slope. C. Sometimes we write predicted in front of the y-variable. D. All of the above. Slide ? - 29 © 2013 Pearson Education, Inc.

The regression line is chosen because, A. It is the line that comes closest to most of the points. B. It provides the best fit to the data. C. The square of the vertical distance between the points and the line, on average, is bigger for any other line we might draw than for the regression line. D. All of the above. Slide ? - 30 © 2013 Pearson Education, Inc.

In the regression line the x-variable is called the A. Explanatory variable. B. Predictor variable. C. Independent variable. D. All of the above. Slide ? - 31 © 2013 Pearson Education, Inc.

In the regression line the y-variable is called the A. Response variable. B. Predicted variable. C. Dependent variable. D. All of the above. Slide ? - 32 © 2013 Pearson Education, Inc.

True or False The slope of a regression line tells us how different the mean y-value is for observations that are 1 unit apart on the x-variable. A. True B. False Slide ? - 33 © 2013 Pearson Education, Inc.

True or False The intercept of a regression line tells us the average y-value for all observations that have a zero x-value. A. True B. False Slide ? - 34 © 2013 Pearson Education, Inc.

True or False An association between two variables is not sufficient evidence to conclude that a cause- and-effect relationship exists between the variables, no matter how strong the correlation or how well the regression line fits the data. A. True B. False Slide ? - 35 © 2013 Pearson Education, Inc.

True or False Outliers can be called influential points because their presence or absence has a big effect on conclusions. A. True B. False Slide ? - 36 © 2013 Pearson Education, Inc.

True or False Extrapolation means that we use the regression line to make predictions beyond the range of our data. This practice can be dangerous, because although the association may have a linear shape for the range we’re observing, that might not be true over a larger range. Slide ? - 37 © 2013 Pearson Education, Inc. A. True B. False

True or False The coefficient of determination is the correlation coefficient squared, r 2, and it measures how well the data fit the linear model. A. True B. False Slide ? - 38 © 2013 Pearson Education, Inc.