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For Exercise 14.1, see page 319; for Exercise 14.2, see page 322; for Exercise 14.3, see page 327.
14.4 Creating scatterplots. When creating a scatterplot,
(a) always put the categorical variable on the horizontal axis.
(b) always put the categorical variable on the vertical axis.
(c) if you have an explanatory variable, put it on the horizontal axis.
(d) if you have a response variable, put it on the horizontal axis.
14.5 Interpreting scatterplots. If the points in a scatterplot of two variables slope upward from left to right, we say the direction of the relationship between the variables is
(a) positive.
(b) negative.
(c) strong.
(d) weak.
14.6 Interpreting scatterplots. Which of the following patterns might one observe in a scatterplot?
(a) The points in the plot follow a curved pattern.
(b) The points in the plot group into different clusters.
(c) One or two points are clear outliers.
(d) All of the above.
14.7 Correlation. Which of the following is true of the correlation r ?
(a) It cannot be greater than 1 or less than −1.
(b) It measures the strength of the straight-line relationship between two quantitative variables.
(c) A correlation of +1 or −1 can only happen if there is a perfect straight-line relationship between two quantitative variables.
(d) All of the above.
14.8 Correlation and scatterplots. If the points in a scatterplot are very tightly clustered around a straight line, the correlation must be
(a) close to 0.
(b) close to +1.
(c) close to −1.
(d) close to either +1 or −1.