Concept explainers
Explain 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
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
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”.
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Chapter 11 Solutions
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- The accompanying data represent the weights (in grams) of a simple random sample of 10 M&M plain candies. Determine the shape of the distribution of weights of M&Ms by drawing a frequency histogram. Find the mean and median. Which measure of central tendency better describes the weight of a plain M&M? Click the icon to view the candy weight data. Draw a frequency histogram. Choose the correct graph below. ○ A. ○ C. Frequency Weight of Plain M and Ms 0.78 0.84 Frequency OONAG 0.78 B. 0.9 0.96 Weight (grams) Weight of Plain M and Ms 0.84 0.9 0.96 Weight (grams) ○ D. Candy Weights 0.85 0.79 0.85 0.89 0.94 0.86 0.91 0.86 0.87 0.87 - Frequency ☑ Frequency 67200 0.78 → Weight of Plain M and Ms 0.9 0.96 0.84 Weight (grams) Weight of Plain M and Ms 0.78 0.84 Weight (grams) 0.9 0.96 →arrow_forwardThe acidity or alkalinity of a solution is measured using pH. A pH less than 7 is acidic; a pH greater than 7 is alkaline. The accompanying data represent the pH in samples of bottled water and tap water. Complete parts (a) and (b). Click the icon to view the data table. (a) Determine the mean, median, and mode pH for each type of water. Comment on the differences between the two water types. Select the correct choice below and fill in any answer boxes in your choice. A. For tap water, the mean pH is (Round to three decimal places as needed.) B. The mean does not exist. Data table Тар 7.64 7.45 7.45 7.10 7.46 7.50 7.68 7.69 7.56 7.46 7.52 7.46 5.15 5.09 5.31 5.20 4.78 5.23 Bottled 5.52 5.31 5.13 5.31 5.21 5.24 - ☑arrow_forwardく Chapter 5-Section 1 Homework X MindTap - Cengage Learning x + C webassign.net/web/Student/Assignment-Responses/submit?pos=3&dep=36701632&tags=autosave #question3874894_3 M Gmail 品 YouTube Maps 5. [-/20 Points] DETAILS MY NOTES BBUNDERSTAT12 5.1.020. ☆ B Verify it's you Finish update: All Bookmarks PRACTICE ANOTHER A computer repair shop has two work centers. The first center examines the computer to see what is wrong, and the second center repairs the computer. Let x₁ and x2 be random variables representing the lengths of time in minutes to examine a computer (✗₁) and to repair a computer (x2). Assume x and x, are independent random variables. Long-term history has shown the following times. 01 Examine computer, x₁₁ = 29.6 minutes; σ₁ = 8.1 minutes Repair computer, X2: μ₂ = 92.5 minutes; σ2 = 14.5 minutes (a) Let W = x₁ + x2 be a random variable representing the total time to examine and repair the computer. Compute the mean, variance, and standard deviation of W. (Round your answers…arrow_forward
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