
Concept explainers
a.
Find the number of variables included in the
Identify whether each of the variables in Figure 2.84(a) is categorical or quantitative.
Estimate the
a.

Answer to Problem 226E
The number of variables included in the scatterplot in Figure 2.84(a) is 2.
Both of the variables are quantitative.
The range for Variable1 is 16.
The range for Variable2 is 90.
Explanation of Solution
From the given scatterplot in Figure 2.84(a), it is clear that there are two variables included, Variable1 in x axis and Variable2 in y axis.
The scales of Variable1 and Variable2 are numerical values. Hence, both of these variables are quantitative.
The minimum and maximum values of the data points observed from the scatterplot for Variable1 are approximately 14 and 29, respectively.
The minimum and maximum values of the data points observed from the scatterplot for Variable2 are approximately 70 and 160, respectively.
The ranges for Variable1 and Variable2 are computed as follows:
Therefore, the range for Variable1 is 16 and the range for Variable2 is 90.
b.
Explain whether the association between the variables appears to be positive or negative in Figure 2.84(a).
b.

Answer to Problem 226E
The association between the variables appears to be positive.
Explanation of Solution
In Figure 2.84(a), as the Variable1 increases, Variable2 also increases. This is an indication of positive association.
Therefore, the association between the variables appears to be positive.
c.
Identify the response variable.
Explain whether the line shows a positive or negative association.
c.

Answer to Problem 226E
The response variable is Variable2.
The regression line shows a positive association.
Explanation of Solution
The variable in the vertical axis represents a response variable and the variable in the horizontal axis represents an explanatory variable.
In Figure 2.84(b), Variable2 is in the vertical axis, whereas Variable1 is in the horizontal axis. Therefore, the response variable is Variable2.
It is also clear from the regression line that the slope of the line is increasing. This indicates that there is a positive association between the variables.
d.
Identify whether the third variable included is categorical or quantitative.
Find the number of categories if it is a categorical variable.
Find the range if it is a quantitative variable.
d.

Answer to Problem 226E
The third variable included is categorical.
The number of categories is 4.
Explanation of Solution
From Figure 2.85(a), the data points are indicated by different symbols, which are labeled as A, B, C, and D. They are non-numerical values. Thus, it is clear that the Variable3 is a categorical variable.
There are four different labels. Thus, the number of categories is 4.
e.
Identify whether the association between Variable1 and Variable2 appears to be positive or negative by considering the case in Group A.
Identify whether the association between Variable1 and Variable2 appears to be positive or negative by considering the case in Group B.
Identify whether the association between Variable1 and Variable2 appears to be positive or negative by considering the case in Group C.
Identify whether the association between Variable1 and Variable2 appears to be positive or negative by considering the case in Group D.
e.

Answer to Problem 226E
The association between Variable1 and Variable2 by considering the case in Group A appears to be negative.
The association between Variable1 and Variable2 by considering the case in Group B appears to be negative.
The association between Variable1 and Variable2 by considering the case in Group C appears to be negative.
The association between Variable1 and Variable2 by considering the case in Group D appears to be negative.
Explanation of Solution
From Figure 2.85 (a), it is clear that the data points of the all categories (A, B, C, and D) are in the decreasing order. That is, as Variable1 increases, Variable2 decreases. Thus, the association between Variable1 and Variable2 is negative by considering Group A, Group B, Group C, and Group D.
f.
Explain whether the regression line for Group A shows a positive or negative association.
Explain whether the regression line for Group B shows a positive or negative association.
Explain whether the regression line for Group C shows a positive or negative association.
Explain whether the regression line for Group D shows a positive or negative association.
f.

Answer to Problem 226E
The regression line for Group A shows a negative association.
The regression line for Group B shows a negative association.
The regression line for Group C shows a negative association.
The regression line for Group D shows a negative association.
Explanation of Solution
In Figure 2.85(b), it is clear from the regression line that the slope of the line is increasing for all the four categories. This indicates the negative association between the variables.
That is, the regression line for Groups A, B, C, and D shows a negative association.
g.
Explain about the difference in the direction of association between Figure 2.84 and Figure 2.85.
g.

Explanation of Solution
In Figure 2.84, the association between variables is positive, while the association between variables is shown as negative in Figure 2.85.
By including additional information contained in Variable3, the association switches from positive to negative.
Want to see more full solutions like this?
Chapter 2 Solutions
STATISTICS-WILEYPLUS ACCESS
- A company found that the daily sales revenue of its flagship product follows a normal distribution with a mean of $4500 and a standard deviation of $450. The company defines a "high-sales day" that is, any day with sales exceeding $4800. please provide a step by step on how to get the answers in excel Q: What percentage of days can the company expect to have "high-sales days" or sales greater than $4800? Q: What is the sales revenue threshold for the bottom 10% of days? (please note that 10% refers to the probability/area under bell curve towards the lower tail of bell curve) Provide answers in the yellow cellsarrow_forwardFind the critical value for a left-tailed test using the F distribution with a 0.025, degrees of freedom in the numerator=12, and degrees of freedom in the denominator = 50. A portion of the table of critical values of the F-distribution is provided. Click the icon to view the partial table of critical values of the F-distribution. What is the critical value? (Round to two decimal places as needed.)arrow_forwardA retail store manager claims that the average daily sales of the store are $1,500. You aim to test whether the actual average daily sales differ significantly from this claimed value. You can provide your answer by inserting a text box and the answer must include: Null hypothesis, Alternative hypothesis, Show answer (output table/summary table), and Conclusion based on the P value. Showing the calculation is a must. If calculation is missing,so please provide a step by step on the answers Numerical answers in the yellow cellsarrow_forward
- MATLAB: An Introduction with ApplicationsStatisticsISBN:9781119256830Author:Amos GilatPublisher:John Wiley & Sons IncProbability and Statistics for Engineering and th...StatisticsISBN:9781305251809Author:Jay L. DevorePublisher:Cengage LearningStatistics for The Behavioral Sciences (MindTap C...StatisticsISBN:9781305504912Author:Frederick J Gravetter, Larry B. WallnauPublisher:Cengage Learning
- Elementary Statistics: Picturing the World (7th E...StatisticsISBN:9780134683416Author:Ron Larson, Betsy FarberPublisher:PEARSONThe Basic Practice of StatisticsStatisticsISBN:9781319042578Author:David S. Moore, William I. Notz, Michael A. FlignerPublisher:W. H. FreemanIntroduction to the Practice of StatisticsStatisticsISBN:9781319013387Author:David S. Moore, George P. McCabe, Bruce A. CraigPublisher:W. H. Freeman





