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Best-paid CEOs. Refer to Glassdoor Economic Research firm’s 2015 ranking of the 40 best-paid CEOs in Table 2.1 (p. 65). Recall that data were collected on a CEO’s age and ratio of salary to a typical worker’s pay at the firm. One objective is to predict the ratio of salary to worker pay based on the CEO’s age.

a. In this study, identify the dependent and independent variables.

b. Explain why a probabilistic model is more appropriate than a deterministic model.

c. Write the equation of the straight-line, probabilistic model.

Short Answer

Expert verified
  1. The dependent variable is the ratio of the CEO’s salary, and the independent variable is the CEO’s age.
  2. There might be some unexpected variances in the dependent variable owing to factors other than the independent variable.
  3. y=β0+β1x+ε.

Step by step solution

01

Introduction

The variable that is tested and quantified in an experiment is called the dependent variable. It depends on the independent variable.

The independent variable is the one that the researcher manipulates or modifies. This variable is supposed to have a direct influence on the dependent variable.

02

Determining which variables are dependent and which are independent

The variable of interest to the researcher is the dependent variable. Therefore, the dependent variable is the ratio of the CEO’s salary.

The independent variable is one that is thought to influence the dependent variable.Therefore; an independent variable is the CEO’s age.

03

Explaining why a probabilistic rather than a deterministic model is more appropriate 

The theory of probability, or the concept that randomness plays a role in forecasting future occurrences, is the foundation of a probabilistic technique or model. A deterministic model, on the other hand, is the polar opposite of a random model. It indicates that something can be anticipated precisely without the addition of randomness.

There are no random components in a deterministic model. The same results are received every time the model is used with identical beginning circumstances. Randomness is present in a probabilistic model. Even with identical beginning circumstances, the model is likely to provide different outcomes each time it is run. A probabilistic model is one that integrates random variation in some way.

We conduct a risk analysis as the CEO's age and salary ratio are unknown. Quantifying that uncertainty with a range of potential values and associated probabilities (i.e., with probability distributions) makes the risks more understandable to everyone. Therefore, there might be some unexpected variance in the dependent variable owing to factors other than the independent variable.

04

Writing the equation for the probabilistic straight-line model

The equation for the probabilistic straight-line model is

y=β0+β1x+ε

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Most popular questions from this chapter

Is honey a cough remedy? Does a teaspoon of honey before bed really calm a child’s cough? To test the folk remedy, pediatric researchers carried out a designed study conducted over two nights (Archives of Pediatrics and Adolescent Medicine, December 2007). A sample of 105 children who were ill with an upper respiratory tract infection and their parents participated in the study. On the first night, the parents rated their children’s cough symptoms on a scale from 0 (no problems at all) to 6 (extremely severe) in five different areas. The total symptoms score (ranging from 0 to 30 points) was the variable of interest for the 105 patients. On the second night, the parents were instructed to give their sick child a dosage of liquid “medicine” prior to bedtime. Unknown to the parents, some were given a dosage of dextromethorphan (DM)—an over-the-counter cough medicine—while others were given a similar dose of honey. Also, a third group of parents (the control group) gave their sick children no dosage at all. Again, the parents rated their children’s cough symptoms, and the improvement in total cough symptoms score was determined for each child. The data (improvement scores) for the study are shown in the table below, followed (in the next column) by a Minitab dot plot of the data. Notice that the green dots represent the children who received a dose of honey, the red dots represent those who got the DM dosage, and the black dots represent the children in the control group. What conclusions can pediatric researchers draw from the graph? Do you agree with the statement (extracted from the article), “Honey may be a preferable treatment for the cough and sleep difficulty associated with childhood upper respiratory tract infection”?

Stability of compounds in new drugs. Testing the metabolic stability of compounds used in drugs is the cornerstone of new drug discovery. Two important values computed from the testing phase are the fraction of compound unbound to plasma (fup) and the fraction of compound unbound to microsomes (fumic). A key formula for assessing stability assumes that the fup/fumic ratio is 1. Pharmacologists at Pfizer Global Research and Development investigated this phenomenon and reported the results in ACS Medicinal Chemistry Letters (Vol. 1, 2010). The fup/fumic ratio was determined for each of 416 drugs in the Pfizer database. An SPSS graph describing the fup/fumic ratios is shown below.

a. What type of graph is displayed?

b. What is the quantitative variable summarized in the graph?

c. Determine the proportion of fup/fumic ratios that fall above 1.

d. Determine the proportion of fup/fumic ratios that fall below .4

Software millionaires and birthdays. Refer to Exercise 11.23 (p. 655) and the study of software millionaires and their birthdays. The data are reproduced on p. 663.

a. Find SSE s2and s for the simple linear regression model relating the number (y) of software millionaire birthdays in a decade to the total number (x) of U.S. births.

b. Find SSE s2and s for the simple linear regression model relating the number (y) of software millionaire birthdays in a decade to the number (x) of CEO birthdays.

c. Which of the two models' fit will have smaller errors of prediction? Why?

Decade

Total U.S. Births (millions)

Number of Software Millionaire Birthdays

Number of CEO Birthdays (in a random sample of 70 companies from the Fortune 500 list)

1920

28.582

3

2

1930

24.374

1

2

1940

31.666

10

23

1950

40.530

14

38

1960

38.808

7

9

1970

33.309

4

0

Refer to Exercise 11.14. After the least-squares line has been obtained, the table below (which is similar to Table 11.2) can be used for (1) comparing the observed and the predicted values of y and (2) computing SSE.

a. Complete the table.

b. Plot the least-squares line on a scatterplot of the data. Plot the following line on the same graph:

y^= 14 - 2.5x.

c. Show that SSE is larger for the line in part b than for the least-squares line.

Why do we generally prefer a probabilistic model to a deterministic model? Give examples for when the two types of models might be appropriate.

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