Steroids The 1990s and early 2000s could be considered the steroids era in Major League Baseball, as many players have admitted to using the drug to increase performance on the field. If a sports writer wanted to compare home run totals from the steroids era to an earlier decade, say the 1960s, explain why this would be an observational study. Could the writer conclude that it was the steroids that caused the increase in home runs? Why or why not?
The reason for the study to be an observational study.
Check whether it is possible to conclude that steroids caused an increase in homeruns.
Answer to Problem 1E
The given study is a retrospective observational study.
No, it is not possible to conclude that the steroids caused an increase in homeruns.
Explanation of Solution
Given info:
A researcher’s wish is to examine the effect of steroids in major league baseball; in general, it is known that most of the players take steroids to increase the performance in the field. For this, the sports writer compares the homeruns and steroids intake from the 1960’s.
Justification:
Observational study:
An observational study measures the values of a variable without influencing the values of response variables and explanatory variables. Thus, in an observational study, researchers can observe the behaviors of the individuals without influencing the outcome of that study.
Here, the researcher ask the individual players whether they take steroids or not and observes their homerun totals. The researchers do not influence the individuals to take steroids but merely observe.
Hence, this is an observational study.
Here, there is a relationship between steroids and homerun totals.
Causation:
If one event is the result of the occurrence of other event, then the variables of the two events are said to be under causation. In other words, it can be said that a causal relationship exists between the two variables.
Even though there is an association between the variables “steroids” and “homerun totals”, the association between the two variables does not infer that the change in one variable is the cause of the change in other variables.
Moreover, the most important thing is that correlation between the two variables does not substantiate the causation.
Lurking variable:
The lurking variable is a type of extraneous variable which is not accounted for under the study. However, it may affect response variables or explanatory variables.
There is a chance for the variables “steroids” and “homerun totals” to not have direct association. The association exists through the lurking variable.
In general case, there is a possibility for the existence of a lurking variable which will be associated with both the variables “steroids” and “homerun totals”.
Therefore, the steroids do not cause homeruns.
Thus, there is no causation between the variables “steroids” and “homerun totals”.
Want to see more full solutions like this?
Chapter 11 Solutions
Intro Stats, Books a la Carte Edition (5th Edition)
- TIP the aren't, the data are not sym 11 Suppose that the average salary at a certain company is $100,000, and the median salary is $40,000. a. What do these figures tell you about the shape of the histogram of salaries at this company? b. Which measure of center is more appro- priate here? c. Suppose that the company goes through a salary negotiation. How can people on each side use these summary statistics to their advantage? 6360 be 52 PART 1 Getting Off to a Statistically Significant Sarrow_forward12 Suppose that you know that a data set is skewed left, and you know that the two measures of center are 19 and 38. Which figure is the mean and which is the median?arrow_forwardy of 45 home- televisions u find that 010020 le own one, ee, and 1 owns y histogram of 4 Suppose that you have a loaded die. You roll it several times and record the outcomes, which are shown in the following figure. Histogram for Loaded Die 444% 34.00 48% 6% 2% Frequency 20 20 15 155 10 5- ம 0 1 2 3 4 Outcome 5 6 a. Make a relative frequency histogram of these results. b. You can make a relative frequency histo- gram from a frequency histogram; can you go the other direction?arrow_forward
- Calculate the mean for Study Hours and Test Scores. Compute the covariance between the two variables using the formula: Calculate the standard deviation for Study Hours (X) and Test Scores (Y). Determine the correlation coefficient Interpret the results: What does the calculated r-value indicate about the relationship between study hours and test scores?arrow_forwardFor unemployed persons in the United States, the average number of months of unemployment at the end of December 2009 was approximately seven months (Bureau of Labor Statistics, January 2010). Suppose the following data are for a particular region in upstate New York. The values in the first column show the number of months unemployed and the values in the second column show the corresponding number of unemployed persons. Months Unemployed Number Unemployed 1 1029 2 1686 3 2269 4 2675 5 3487 6 4652 7 4145 8 3587 9 2325 10 1120 Let x be a random variable indicating the number of months a person is unemployed. a. Use the data to develop an empirical discrete probability distribution for x (to 4 decimals). (x) f(x) 1 2 3 4 5 6 7 8 9 10 b. Show that your probability distribution satisfies the conditions for a valid discrete probability distribution. The input in the box below will not be graded, but may be reviewed and considered by your instructor. blank c. What is the probability that a…arrow_forwardWest Virginia has one of the highest divorce rates in the nation, with an annual rate of approximately 5 divorces per 1000 people (Centers for Disease Control and Prevention website, January 12, 2012). The Marital Counseling Center, Inc. (MCC) thinks that the high divorce rate in the state may require them to hire additional staff. Working with a consultant, the management of MCC has developed the following probability distribution for x = the number of new clients for marriage counseling for the next year. Excel File: data05-19.xls x 10 f(x) .05 20 30 .10 .10 40 .20 50 60 .35 .20 a. Is this probability distribution valid? - Select your answer- Explain. f(x) Σf(x) Select your answer Select your answer b. What is the probability MCC will obtain more than 30 new clients (to 2 decimals)? c. What is the probability MCC will obtain fewer than 20 new clients (to 2 decimals)? d. Compute the expected value and variance of x. Expected value Variance clients per year squared clients per yeararrow_forward
- For unemployed persons in the United States, the average number of months of unemployment at the end of December 2009 was approximately seven months (Bureau of Labor Statistics, January 2010). Suppose the following data are for a particular region in upstate New York. The values in the first column show the number of months unemployed and the values in the second column show the corresponding number of unemployed persons. Months Unemployed Number Unemployed 1 1029 2 1686 3 2269 4 2675 5 3487 6 4652 7 4145 8 3587 9 2325 10 1120 Let x be a random variable indicating the number of months a person is unemployed. a. Use the data to develop an empirical discrete probability distribution for x (to 4 decimals). (x) f(x) 1 2 3 4 5 6 7 8 9 10 b. Show that your probability distribution satisfies the conditions for a valid discrete probability distribution. The input in the box below will not be graded, but may be reviewed and considered by your instructor. c. What is the probability that a person…arrow_forwardIn Gallup's Annual Consumption Habits Poll, telephone interviews were conducted for a random sample of 1014 adults aged 18 and over. One of the questions was "How many cups of coffee, if any, do you drink on an average day?" The following table shows the results obtained (Gallup website, August 6, 2012). Excel File: data05-23.xls Number of Cups per Day Number of Responses 0 365 264 193 3 4 or more 91 101 Define a random variable x = number of cups of coffee consumed on an average day. Let x = 4 represent four or more cups. Round your answers to four decimal places. a. Develop a probability distribution for x. x 0 1 2 3 4 f(x) b. Compute the expected value of x. cups of coffee c. Compute the variance of x. cups of coffee squared d. Suppose we are only interested in adults that drink at least one cup of coffee on an average day. For this group, let y = the number of cups of coffee consumed on an average day. Compute the expected value of y. Compare it to the expected value of x. The…arrow_forwardIn Gallup's Annual Consumption Habits Poll, telephone interviews were conducted for a random sample of 1014 adults aged 18 and over. One of the questions was "How many cups of coffee, if any, do you drink on an average day?" The following table shows the results obtained (Gallup website, August 6, 2012). Excel File: data05-23.xls Number of Cups per Day Number of Responses 0 365 264 193 2 3 4 or more 91 101 Define a random variable x = number of cups of coffee consumed on an average day. Let x = 4 represent four or more cups. Round your answers to four decimal places. a. Develop a probability distribution for x. x 0 1 2 3 f(x) b. Compute the expected value of x. cups of coffee c. Compute the variance of x. cups of coffee squared d. Suppose we are only interested in adults that drink at least one cup of coffee on an average day. For this group, let y = the number of cups of coffee consumed on an average day. Compute the expected value of y. Compare it to the expected value of x. The…arrow_forward
- A technician services mailing machines at companies in the Phoenix area. Depending on the type of malfunction, the service call can take 1, 2, 3, or 4 hours. The different types of malfunctions occur at about the same frequency. Develop a probability distribution for the duration of a service call. Duration of Call x f(x) 1 2 3 4 Which of the following probability distribution graphs accurately represents the data set? Consider the required conditions for a discrete probability function, shown below.Does this probability distribution satisfy equation (5.1)?Does this probability distribution satisfy equation (5.2)? What is the probability a service call will take three hours? A service call has just come in, but the type of malfunction is unknown. It is 3:00 P.M. and service technicians usually get off at 5:00 P.M. What is the probability the service technician will have to work overtime to fix the machine today?arrow_forwardA psychologist determined that the number of sessions required to obtain the trust of a new patient is either 1, 2, or 3. Let x be a random variable indicating the number of sessions required to gain the patient's trust. The following probability function has been proposed. x f(x) for x = 1, 2, or 3 a. Consider the required conditions for a discrete probability function, shown below. f(x) ≥0 Σf(x) = 1 (5.1) (5.2) Does this probability distribution satisfy equation (5.1)? Select Does this probability distribution satisfy equation (5.2)? Select b. What is the probability that it takes exactly 2 sessions to gain the patient's trust (to 3 decimals)? c. What is the probability that it takes at least 2 sessions to gain the patient's trust (to 3 decimals)?arrow_forwardA technician services mailing machines at companies in the Phoenix area. Depending on the type of malfunction, the service call can take 1, 2, 3, or 4 hours. The different types of malfunctions occur at about the same frequency. Develop a probability distribution for the duration of a service call. Which of the following probability distribution graphs accurately represents the data set? Consider the required conditions for a discrete probability function, shown below.Does this probability distribution satisfy equation (5.1)?Does this probability distribution satisfy equation (5.2)? What is the probability a service call will take three hours? A service call has just come in, but the type of malfunction is unknown. It is 3:00 P.M. and service technicians usually get off at 5:00 P.M. What is the probability the service technician will have to work overtime to fix the machine today?arrow_forward
- Big Ideas Math A Bridge To Success Algebra 1: Stu...AlgebraISBN:9781680331141Author:HOUGHTON MIFFLIN HARCOURTPublisher:Houghton Mifflin HarcourtGlencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw HillHolt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGAL
- College Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage Learning