Statistics homework help
Question 1
1.
The frameworks discussed in Chapter 4 could be considered more specific examples of:
Answer
| The Statistical Thinking Strategy | ||
| Statistical engineering | ||
| The scientific method | ||
| All of the above | ||
| None of the above |
4 points
Question 2
1.
After running an ANOVA comparing the average years of experience between five different job classifications, we obtained a p value of .02. Which of the following would be a reasonable conclusion concerning the population in this case?
Answer
| We have strong evidence to state that the average years of experience between these job classifications is the same | ||
| We have insufficient evidence to state that the average years of experience between these job classifications is the same | ||
| We have strong evidence to state that each of the job classifications has a different average age | ||
| We have strong evidence to state that at least two of the job classifications have different average ages | ||
| None of the above |
4 points
Question 3
1.
We are testing the null hypothesis that the average monthly revenue between four insurance offices is the same. We obtained a p-value of .07. Which of the following would be an appropriate conclusion about the population?
Answer
| There is a difference between the average monthly revenues of at least two of the offices | ||
| There is no difference between the average monthly revenues of the four offices | ||
| All of the offices have different average monthly revenue | ||
| There is a 93% chance that at least one of the average monthly revenues of one of the offices is different from the others | ||
| None of the above |
4 points
Question 4
1.
For which of the following scenarios am I most likely to utilize a Chi-squared test?
Answer
| Comparing the proportion of employees who take 10 or more sick days a year between three manufacturing plants | ||
| Comparing the amount of variation in age between employees at four call centers | ||
| Determining if there is any evidence that an independent variable has a relationship with y in a multiple regression model | ||
| Comparing the average retirement age between hourly workers and management | ||
| None of the above |
4 points
Question 5
1.
What would happen (other things equal) to a confidence interval if you calculated a 99 percent confidence interval rather than a 95 percent confidence interval?
Answer
| It will be narrower | ||
| It will not change | ||
| The sample size will increase | ||
| It will become wider | ||
| None of the above |
4 points
Question 6
1.
We ran a taste-test to see which soft drink employees in our company prefer. We had 100 employees, selected as randomly as possible, taste test two brands and determine which they preferred. Which of the following would be a reasonable statistical analysis to determine if there is a clear preference among our employees?
Answer
| A two sample t-test | ||
| A paired t test | ||
| A confidence interval for a proportion | ||
| A prediction interval for a proportion | ||
| None of the above |
4 points
Question 7
1.
Results of regression analysis are often abused in the following ways:
Answer
| Using the model without understanding the context in which the model was developed and recommended for use | ||
| Predicting outside the region of the data without noting the predictions are an extrapolation of the model | ||
| Ignoring known scientific and economic theory regarding the model and its variables | ||
| All of the above | ||
| None of the above |
4 points
Question 8
1.
Models based on subject matter fundamentals (theory) are generally better than statistical models for:
Answer
| Deep understanding of the process being modeled | ||
| Extrapolation – Predicting outside the region of the available data | ||
| Quick development of models | ||
| A and B | ||
| All of the above | ||
| None of the above |
4 points
Question 9
1.
If you had the following residual plots what would be your concerns regarding the adequacy of the model associated with these residuals?
Answer
| Model is adequate. There is nothing of concern in the residual plots | ||
| No problem, the residuals are normally distributed | ||
| Residuals plots exhibit curvature versus the fitted value, but that is not a big problem | ||
| Residuals plots have non-random patterns suggesting that the model is not adequate. | ||
| None of the above |
4 points
Question 10
1.
George Box tells us “all models are wrong but some are useful”. By this comment he means:
Answer
| Humans do not have the capability to develop good models | ||
| Models approximate the underlying theory and can be useful in some situations | ||
| We can never model the true state of nature | ||
| B and C | ||
| None of the above |
4 points
Question 11
1.
Tips for building useful models include:
Answer
| Reducing subjectivity by using computer algorithms to select model predictor variables | ||
| Plotting the raw data and model residuals in a variety of ways | ||
| Focus on keeping the models simple, not complex | ||
| Validating the performance of the model | ||
| A, B and C above | ||
| B, C and D above | ||
| None of the above |
4 points
Question 12
1.
What should one consider when analyzing the results of an experiment?
Answer
| Understanding of the science, technology and operation of the process being studied | ||
| Creating graphical displays to aid in the analysis and interpretation of the results of the experiment | ||
| Performing a statistical analysis to test the significance of the effects studied in the experiment | ||
| All the above | ||
| None of the above |
4 points
Question 13
1.
Identify the assumption that is NOT made when conducting an experiment:
Answer
| The measurement system is capable for all measured responses | ||
| The factors being varied are those studied in the experiment. All other factors are being held constant. | ||
| The process remains relatively stable during the duration of the testing | ||
| The experimental variation is small | ||
| None of the above |
4 points
Question 14
1.
A 32 experiment means that we are experimenting with:
Answer
| Two levels of three factors | ||
| Two dependent variables and three independent variables | ||
| Two go/no-go variables and three continuous variables | ||
| Three levels of two factors | ||
| None of the above |
4 points
Question 15
1.
Given the plot below, what might you suspect about factors A and B?
Answer
| The effect of A is not influenced by the level of B | ||
| The effect of A depends on the level of B | ||
| A has a larger effect on the response than B | ||
| B has a larger effect on the response than A | ||
| None of the above |
4 points
Question 16
1.
Which of the following purposes are served by replicating an experiment?
| 1. | Provide a means for estimating the experimental error |
| 2. | Increase the number of treatment effects included in the experiment |
| 3. | Improve the precision of estimates of treatments effects |
Answer
| 1 and 2 only | ||
| 1 and 3 only | ||
| 2 and 3 only | ||
| All the above | ||
| None of the above |
4 points
Question 17
1.
In evaluating data on our process outputs, four characteristics we might investigate are: central tendency, variation, shape of distribution, and stability. Which of the following tools would be most helpful to determine stability of the process?
Answer
| Scatter plot | ||
| Histogram | ||
| Pareto chart | ||
| Run chart | ||
| None of the above |
4 points
Question 18
1.
In evaluating data on our process outputs, four characteristics we might investigate are: central tendency, variation, shape of distribution, and stability. Which of the following tools would be most helpful to determine the shape of the distribution?
Answer
| Scatter plot | ||
| Histogram | ||
| Pareto chart | ||
| Run chart | ||
| None of the above |
4 points
Question 19
1.
Control limits were originally defined at the three-sigma level because:
Answer
| This level provides a good balance between the risks of having “false alarms” and missing special causes | ||
| This level establishes tight limits for the process to minimize variation | ||
| This level provides only 3 false alarms out of 1,000 | ||
| This level makes it difficult for special causes to occur | ||
| None of the above |
4 points
Question 20
1.
What does it mean if capability index Cp is less than 1?
Answer
| Process spread is greater than the specification | ||
| It is safe to assume the process will most likely meet or exceed the specification | ||
| The process is unstable | ||
| The process is off target | ||
| None of the above |
4 points
Question 21
1.
A process is said to be capable if:
Answer
| The process consistently meets the customers needs | ||
| The common cause variation is less than +/- 3σ | ||
| The common cause variation fits within the specification limits | ||
| The process is experiencing no special causes | ||
| None of the above |
4 points
Question 22
1.
The Hidden Factory is:
Answer
| Where the real work is done; out of the view of the public | ||
| A source of Increased costs and reduced process capacity | ||
| Only present in manufacturing processes | ||
| Created by the workforce to cover up mistakes and errors | ||
| All of the above | ||
| None of the above |
4 points
Question 23
1.
The primary goal of process mapping is to:
Answer
| Understand how the process as it is actually operated | ||
| Create a context for problem solving | ||
| Document the process steps including beginning and end | ||
| All of the above | ||
| None of the above |
4 points
Question 24
1.
Problem solving activities typically include:
Answer
| Reducing the number of persons employed by an organization | ||
| Automating The process to remove the problem | ||
| Find the person(s) who are causing the problems and take appropriate action | ||
| All of the above | ||
| None of the above |
4 points
Question 25
1.
Box, Hunter, and Hunter are quoted in this chapter as stating: “Data have no meaning in themselves; they are meaningful only in relation to a conceptual model of the phenomenon studied.” This critical point is related to which of the following principles of statistical thinking?
Answer
4 points
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