Statistics exam help

Instructions

Final Exam – MGMT 650 Fall 2016   Directions: Please answer all questions. There are 30 questions and the exam is worth 20% of your total grade. The questions are not equally weighted. The point value for each question is listed below (100 points total). Data needed to complete the exam are contained in this Excel file. All answers are to be contained in one excel file. You can save this file under your name and complete the work within this file. Please do not delete this tab, the instructions tab. This is an open book, open notes exam. The one limitation is that you may NOT work with other people. This test must be completed independently. Show your work to gain partial credit. Be sure your name is on your document. Good luck!

Q1 through 13

Q5. The two most important aspects of precision are reliability and validity. Validity refers to __________ A. “….the agreement between the value of a measurement and its true value.” B. “….the reproducibility of a measurement.”

Q4. Let’s assume we know that 1% of women over the age of 40 have breast cancer. Let’s assume that 90% of women who have breast cancer will test positive for breast cancer in a mammogram. Eight percent of women that do NOT have breast cancer will also test positive. What is the probability of having cancer if you have a positive test (Select the correct answer from the choices below.) A. 0.90 B. 0.01 C. 0.10 D. 0.08

Q2: Match the appropriate inferential statistical test to the provided definitions.

A. t test B. ANOVA C. Chi-Square

1. Used to test independence for more than 2 means (i.e. compares the means of more than 2 groups) Letter: _______ 2. Used to test the independence between 2 or more categorical variables Letter: _______ 3. Used to compare means of 2 groups Letter: _______

Q3: What is the risk of performing the t=test using pooled variance, if the variances between the 2 samples are actually unequal (i.e.. fail the F test) ? A. Your result will only be applicable for a one-tail t-test B. You will fail to adjust for sample size. C. You may falsely accept or reject the null hypothesis.

Q1. Central tendency is most commonly referred to as the numberical center of the data set: Which of these are common representations of central tendency A. Mean B. Variance C. Mode D. Median E. Range F. Standard Deviation

Q6. According to the empirical rule, if the data form a “bell-shaped curve” (normal distribution), approximately what percent of the observations will be contained within + /- 2 standard deviations from the arithmetic mean. (Select the correct answer from the choices below.) A. 99.7 B. 95.0 C. 75.0 D. 68.3

Q7. A new drug is created to help people with depression. When testing the drug, what are the null and alternative hypotheses? A. Ho: As a result of 300mg./day of the ABC drug, there will be no significant difference in depression. HA: As a result of 300mg/day of the ABC drug, there will be a significant difference in depression. B. Ho: As a result of 300mg./day of the ABC drug, there will be a significant difference in depression. HA: As a result of 300mg/day of the ABC drug, there will be no significant difference in depression.

Q8. The data are the areas of lawns in square feet. You sample five houses. The areas of the lawns are 144 sq. feet, 160 sq. feet, 190 sq. feet, 180 sq. feet, and 210 sq. feet. What type of data is this? A. Quantitative continuous data B. Quantitative discrete data C. Qualitative data D. Binomial Distribution data

Q9. During an election year, we see articles in the newspaper that state confidence intervals in terms of proportions or percentages. For example, a poll for a particular candidate running for president might show that the candidate has 40% of the vote within 3 percentage points. This election polls was calculated with 95% confidence. Is there a 40% chance that this candidate will be elected? A) Yes, and we are 90% sure of it. B) Yes, and we are 95% sure of it. C) We are 95% sure that the chance this candidate will be elected is between 37% and 43% D) Maybe. 40% is a believable value of the proportion based on the information given. E) No. The proportion is 43%. F) No, and we are 90% sure of it. G) No, and we are 95% sure of it.

Q10. This question is related to simple linear regression. In simple linear regression, the goal is to determine if there is a linear change in the _______ variable based on a change in the ______ variable. The dependent variable will always be a ________ variable. If a negative relationship is found, this means that as the independent variable _______, the dependent variable _______. (Select the correct answer from the choices below to correctly fill in the blank words.) A. dependent, independent, categorical, increases, decreases B. independent, dependent, categorical, increases, decreases C. dependent, independent, numerical, increases, decreases D. dependent, independent, numerical, increases, increases E. independent, dependent, numerical, decreases, increases

Q11. What is the function in Excel used to find the mean? A. =MEAN() B. =AVERAGE()

Q12. What is the algebraic equation for the coefficient of variation? A. Variance / mean B. Variance * mean C. Standard deviation / mean D. Standard deviation * mean

Q13. If you toss a die twice, what is the sample space if you want to restrict the results to only the ones where adding the results of the two throws together equals seven? For example, if you get 1 on the first toss and 6 on the second toss these two tosses meet the criteria. A. S = {(1,6), (2,5), (3,4)} B. S = {(1,6), (2,5), (3,4), (4,3), (5,2), (6,1)} C. S = {7} D. S = {2,5), (5,2), (1,6), (6,1)} E. S = (1,6), (2,5), (3,4)

Q14 through 26

Q14: Choose all answers that describe an array function in Excel. A. Uses curly braces B. Uses parentheses C. Elements in a vertical array are separated by commas D. Elements in a vertical array are separated by semicolons E. You must use other computer keys besides return to create the function F. One array function is =FREQUENCY() G. One array function is =STDEV.P()

Q15: The probability that you will throw boxcars (two 6’s) with one throw using 2 dice is A. .028 B. .17 C. .33

Q16: Suppose that a 90% confidence interval states that the population mean is greater than 100 and less than 200. How would you interpret this statement? A. We are 90% sure that the population mean is less than 200. B. We would expect 90% of the interval estimates to include the population parameter.

Q17: Whch statistics distributions are based on the normal curve? Choose all that apply. A. Student’s t distribution B. Chi Square distribution C. Monica’s Z distribution D. F distribution E. G distribution

Q18: Which one is correct for bivariate data? A. If the measurements are categorical (e.g. Yes or No to the question “Do you smoke?”) and taken from two distinct group (e.g. Female, Male) the analysis will involve comparing two independent means. B. If the measurements are quantitative (e.g. GPA) and taken from two distinct groups (e.g. Graduate, Undergraduate) the analysis will involve comparing two independent proportions. C. If the measurements are quantitative (e.g. Weight) and taken twice from each subject (e.g. subject’s weight before and after dieting) the analysis will involve comparing two dependent means.

Q19: What is the null hypothesis that ANOVA tests? A. H(0): All the population means are equal B. H(0): There is a difference between the means of the populations

Q20: Given the following totals column, what are the esxpected values, assuming homogeneity or independence.?

Q21: Which of the following are functions with x denoting the independent variable and y denoting the dependent variable? Choose all that apply. A. y = f(x) B. x = f(y) C. y = a + bx

Q22: A car dealer measures the number of cars sold by each salesperson in January. This data is: A. Time series B. Cross sectional C. Numerical D. Categorical

Q23: Which statement(s) is/are false about the Chi Square distribution? A. As the degrees of freedom increases, the Chi Square distribution approaches a normal distribution. B. The chi-square distribution is always right skewed, regardless of the value of the degrees of freedom parameter. C. The chi-square statistic is always positive. D. As the degrees of freedom increases, the shape of the chi-square distribution becomes more skewed.

Q24: Which of the following is a paired sample? A. Ten pairs of data were taken measuring zinc concentration in bottom water and surface water. B. Randomly select 20 males and 20 females and compare the average time they spend watching TV.

Q25: In statistics, what does MSE stand for? A. Mean-Square Error B. Multiple-Square Error C. Mean-statistical Error D. Multiple-statistical Error

Q26: A UMUC professor wants to determine if her students are getting taller. She obtains the height of 50 of her students over the years. What is the df? A. 51 B. 50 C. 49 D. 100 E. 98

Q27

Q27. The wait times for an oil change are given in columns A and B. A. Generate a frequency distribution of 10 Bins for wait times for an oil change. Use the =MIN() , =MAX(), and =FREQUENCY() functions. B.Make sure the graph includes a title. Label the x and y axis. C. Suppose a customer is selected at random. Let A = the event the customer’s wait is less than 16 minutes. Find the probability of A.

Q28

Q28. Find the confidence limit for these values 51, 53, 49, 43, 47, 46, 45, 30, 60, 52. a) Using α = .05, test the hypothesis using the confidence limits that the true mean is 50 against the alternative that the true mean is not 50. Show your work. b) State the conclusion.

Q29

Q29. Refer to the tab titled “Service Satisfaction” for data required to solve this problem. You are looking at results of a survey of customer satisfaction with their service department from 2 different Car Dealerships. Forty customers from each dealership took a survey related to their satisfaction after getting their brakes cleaned and serviced. The survey results were calculated on a scale from 0 to 10, with 10 indicating complete satisfaction. The Dealerships are titled Dealership A and Dealership B. You want to know if customer satisfaction in the service department was the same or different based on the dealership. Answer questions 1 through 3 below.

#1. What is your null hypothesis (H0) for this research topic? (Select either A or B from below.) A. Customer satisfaction is dependent on which dealership did the brake work. B. There is no difference in customer satisfaction related to the service experience in Dealership A or Dealership B.

#2. Calculate the mean of the customer satisfaction score for each dealership. A. ______ Dealership A customer satistaction B. ______ Dealership B customer satisfaction

#3. Perform the appropriate statistical test to test for significance between the the two groups. Note, use “data analysis” to get your result. Based on your results: A. What p-value did you find and is this significant? B. Would you accept or reject the null hypothesis?

Q30

Q30. Refer to the tab titled “Yarn Purchased” for data required to solve this problem. This data represents the number of skeins bought with 4 different colors of the same yarn per customer. Answer questions 1 through 2 below.

#1. What is an appropriate null hypothesis (H0) for this data analysis? A. There is a significant difference in customer color preferences for the yarn. B. There is no difference in color preference for the 4 different colors of yarn.

#2. Perform a one-way ANOVA to test for significant difference in color preference between the 4 colors. Use the data analysis tool to perform the test. You will need to rearange the data to be able to run the test appropriately. You can create a new tab with the data ordered in the way that is required to run this test.) Based on the p-value from your ANOVA test, would you accept or reject your null hypothesis ? Explain why.

Service Satisfaction

Yarn Purchased