Biostatistics questions
Paper , Order, or Assignment Requirements

A study is conducted to test a new drug claimed to reduce diastolic blood pressure in adults with a history of coronary heart disease. What is the most efficient study to test whether the drug reduces diastolic blood pressure? Justify your answer.

An investigator wants to test whether exposure to secondhand smoke before 1 year of life is associated with development of childhood asthma (defined as asthma diagnosed before 5 years of age). Give two possible study designs and indicate the pros and cons of each. Then, provide your recommendation for the most efficient design.

True or False? The following are all examples of observational study designs:
Case-control study.
Prospective cohort study.
Cross-over trial.
Retrospective cohort study.

A study is run to estimate the incidence of atrial fibrillation (AF) in men and women over the age of 60. Development of atrial fibrillation was monitored over a 10-year follow-up period. The data are summarized below:

Developed AF Did not Develop AF
Men 120 6453
Women 86 7074

Compute the cumulative incidence of AF in men and in women.
Compute the relative risk of AF incidence comparing men to women.
Compute the odds ratio of AF incidence comparing men and women.

A clinical trial designed to show the efficacy of a new drug in reducing progression to hypertension reports the following:

New Drug Placebo
Sample size 200 200
Progression to hypertension 14% 19%

Compute the relative risk of progression to hypertension among patients receiving the new drug as compared to the placebo.
Compute the difference in proportions of patients progressing to hypertension between the two groups.

The following are grade point averages measured in a sample of 8 undergraduate students who are applying to graduate schools in public health.
3.28 2.97 3.05 3.61 3.39 2.95 3.00 3.10

Compute the sample mean.
Compute the sample standard deviation.
Compute the sample median.

The following are body mass index (BMI) scores measured in 12 patients who are free of diabetes and participating in a study of risk factors for obesity. Body mass index is measured as the ratio of weight in kilograms to height in meters squared.
25 27 31 33 26 28 38 41 24 32 35 40

Compute the mean BMI.
Compute the standard deviation of BMI.
Compute the median BMI.
Compute Q1 and Q3.
Are there outliers in the distribution of BMI? Justify your answer.

A pilot study is run to investigate the effect of a lifestyle intervention designed to increase medication adherence in patients with HIV. Medication adherence is measured as the percentage of prescribed pills that are taken over a one week observation period. Ten patients with HIV agree to participate and their medication adherence before and after the intervention are shown below.

Participant ID Before Intervention After Intervention
1 75% 80%
2 82% 84%
3 66% 70%
4 74% 70%
5 88% 90%
6 66% 75%
7 51% 60%
8 93% 90%
9 88% 90%
10 91% 95%
Compute differences in adherence before versus after the intervention for each participant.
Compute the mean difference in adherence before versus after the intervention.
Compute the standard deviation of the difference in adherence before versus after intervention.

True or False? For the standard normal distribution, Q3 = 0.675.

A random sample of eight adults, aged 30 years, were asked how much they spent on medical costs in the year 2009. The following data were measured.
300 140 5600 520 470 700 640 1200

Compute the sample mean.
Compute the sample standard deviation.
Compute the sample median.
Compute the first and third quartiles.

Glucose levels in patients free of diabetes are assumed to follow a normal distribution with a mean of 120 and a standard deviation of 16.
What proportion of patients has glucose levels exceeding 115?
If a patient has a glucose level of 140, what percentile is this?
What is the probability that the mean glucose level exceeds 115 in a sample of 12 patients?

The following table shows the numbers of patients classified as underweight, normal weight, overweight, and obese, according to their diabetes status.

Underweight Normal Weight Overweight Obese
Diabetes 8 34 65 43
No Diabetes 12 85 93 40

If a patient is selected at random:

What is the probability that they are overweight?
What is the probability that they are obese and diabetic?
What proportion of the diabetics is obese?
What proportion of normal-weight patients are not diabetic?
What proportion of patients is normal weight or underweight?

Approximately 30 percent of obese patients develop diabetes. If a physician sees 10 patients who are obese:
What is the probability that half of them will develop diabetes?
What is the probability that none will develop diabetes?
How many would you expect to develop diabetes?

The following table shows the distribution of BMI in children living in U.S. and European urban neighborhoods. (The data are in millions.)

Neighborhood Normal Weight Overweight Obese
US 125 50 40
Europe 101 42 21

Suppose that the probability that a child living in an urban area in the US is obese is 20 percent. A social worker sees 15 children living in urban areas,

What is the probability that none are obese?
What is the probability that 5 are obese?

BMI in children is approximately normally distributed with a mean of 24.5 and a standard deviation of 6.2.
A BMI between 25 and 30 is considered overweight. What proportion of children is overweight?
A BMI of 30 or more is considered obese. What proportion of children is obese?
In a random sample of 10 children, what is the probability that their mean BMI exceeds 25?

The following data were collected in a survey of 8th graders and summarize their cell phone status.

No cell phone Conventional cell phone user Smart phone user
Boys 55 65 35
Girls 31 78 27

What proportion of the 8th graders has cell phones?
What proportion of the boys does not have cell phones?
Is ownership of a cell phone independent of sex? Justify your answer.
What proportion of smart phone users are boys?

A ferritin test is a popular test to measure a person’s current iron stores. In women, ferritin is approximately normally distributed with a mean of 89 ng/mL and a standard deviation of 23 ng/mL.
What is the probability that a woman has a ferritin value of 100 or less?
If a woman has a ferritin of 140, what percentile is this?
If 50 women are tested, what is the probability that the mean ferritin exceeds 90?
With a binomial distribution with n=25 and p=0.48, which is larger:
P(12 successes).
P(9 successes).
P(20 successes).
P(10 successes).

The following table shows the results of a screening test hypothesized to detect persons at risk for side effects of a new cosmetic surgery.

Side effects present Side effects absent
Screen positive 12 6
Screen negative 85 204

Compute the sensitivity of the test.
Compute the specificity of the test.
Compute the false positive fraction.
Compute the false negative fraction.

The following table shows the results of a screening test hypothesized to identify persons at risk for a rare blood disease.

No Disease Disease
Screen Negative 1274 28
Screen Positive 51 45

Compute the sensitivity of the test.
Compute the specificity of the test.
Compute the false positive fraction.
Compute the false negative fraction.

 

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Statistics Springdale Shopping Survey
Paper , Order, or Assignment Requirements

Option 1: Springdale Shopping Survey

Instructions

The major shopping areas in the community of Springdale include Springdale Mall, West Mall, and the downtown area on Main Street. A telephone survey has been conducted to identify strengths and weaknesses of these areas and to find out how they fit into the shopping activities of local residents. The 150 respondents were also asked to provide information about themselves and their shopping habits. The data are provided in the file SHOPPING. The variables in the survey can be found in the file CODING.

We will concentrate on variables 18–25, which reflect how important each of eight different attributes is in the respondent’s selection of a shopping area. Each of these variables has been measured on a scale of 1 (the attribute is not very important in choosing a shopping area) to 7 (the attribute is very important in choosing a shopping area). The attributes being rated for importance are listed below. Examining the relative importance customers place on these attributes can help a manager “fine-tune” his or her shopping area to make it a more attractive place to shop.

18 Easy to return/exchange goods

19 High quality of goods

20 Low prices

21 Good variety of sizes/styles

22 Sales staff helpful/friendly

23 Convenient shopping hours

24 Clean stores and surroundings

25 A lot of bargain sales

Perform the following operations for variables 18–25:
Compute descriptive statistics (5-number summary, mean, mode, range and standard deviation) for each variable along with an explanation of what the descriptive statistics tell us about the variable.
Are there any data points for any of the variables that can be considered outliers? If there are any outliers in any variable, please list them and state for which variable they are an outlier. Use the z-score method to determine any outliers for this question.
Based on the results for question 1, which attributes seem to be the most important and the least important in respondents’ choice of a shopping area? Which items from #1 did you use to decide on the least and most important attributes, and why?
Determine the correlation coefficient between variable 19 and variables 21 – 25. Please provide an explanation of the relationships.
Paper Requirements

Write a report that applies the APA Writing Format 6th Edition. Items that should be included, at a minimum, are a title page, an introduction, a body which answers the questions posed in the problem, and a conclusion paragraph that addresses your findings and what you have determined from the data and your analysis. As with all written assignments, you should have in-text citations and a reference page too. Please include any tables of calculations, calculated values and graphs associated with this problem in the body of your assignment response.

 

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Statistics homework. Only look at this if you have (IBM SPSS Statistics 24)
Paper , Order, or Assignment Requirements

(a) What are the steps involved in hypothesis testing? (b) How do you decide what the null hypothesis is and when would you reject a null hypothesis? (c) if you fail to reject the null hypothesis, what would be its implications? (5 pts.)

The average work week for Americans has been recorded as 43 hours nationally. A local leisure product marketer randomly selects 44 sales people and asks them to keep a log book of hours worked. Suppose the sample average turns out to be 40.5 hours with a standard deviation of 9 hours. Conduct a hypothesis testing for the claim that Americans are now working less (show all steps and use 95 % confidence). Discuss the potential business implications from your result (10 pts- 7 pts for hypothesis testing and 3 pts for business implications).

In 2014, the average number of years passenger cars were being used was 6.5 years. In 2015, a sample of 100 passenger cars showed a sample mean of 7.8 years and a sample standard deviation of 2.2 years. Use a .05 level of significance (p< .05) and test the claim that people use their cars for longer period of time. What marketing suggestions do you have for vehicle manufacturers? (10 pts- 7 pts for hypothesis testing and 3 pts for business implications).

Q-Mart is interested in comparing its male and female customers. Q-Mart would like to know if its female customers spend more money, on average, than its male customers. They have collected random samples of 25 female customers and 22 male customers. On average, women customers spend $102.23 with a sample standard deviation of 93.4 and men customers spend $86.46 with a sample standard deviation of 59.7. Using a 10% level of significance, is there sufficient evidence for Q-Mart to conclude that women customers on average spend more than men customers? Please advise Q-Mart about potential business implications (10 pts- 7 pts for hypothesis testing and 3 pts for business implications).

Suppose a Lightco produces light bulbs and wants to know whether it can claim that its light bulbs typically last more than 1500 hours. Hoping to find support for their claim, the firm collects a random sample of 25 lightbulbs and records the lifetime (in hours) of each bulb. The sample mean was 1509.5 hours with a sample standard deviation of 4.84. If you were to use 1 % significance level in this case, would you conclude that the mean life of the light bulbs is typically more than 1500 hours ? Please advise (10 pts- 7 pts for hypothesis testing and 3 pts for business implications).
Please open the Santa Fe Grill dataset on SPSS and answer the following questions.

6.a The owners of the Santa Fe Grill want to find out whether their female customers have different opinions on several factors than their male customers: Fresh food (X_15), Food Taste (X_18), Friendly Employees (X_12). They are also curious whether it is the same for Jose’s customers. Set the hypothesis, report the SPSS analysis findings and advise Santa Fe Grill owners about potential implications (10 pts – 6 points setting the hypothesis and running the proper analysis, 4 points for the business advise).

b The owners of the Santa-Fe Grill noticed that their customers may have a higher likelihood of returning to the restaurant (X_23) than recommending the restaurant to their family and friends (X_24). Since these two variables are likely to be related, they want to know if the ratings for likely to return are significantly higher (more favorable) than for recommending the restaurant. They also would like to know what Jose’s customers are inclined to do in the same case. Choose the appropriate statistical test that allows you to examine whether two means from these two different questions answered by the respondents are significantly different. Set the hypothesis, report the SPSS analysis findings and advise Santa Fe Grill owners about potential implications (15 pts – 10 points setting the hypothesis and running the proper analysis, 5 points for the business advise).

6.c Santa Fe Grill owners want to find out whether their advertisements make a difference in their customers’ satisfaction level (X22), likelihood to come back (X23), and likelihood to recommend (X24). They decided to ask their customers whether they remember the advertisements (X31_ad recall), they also ask them whether they are satisfied with the service (X22), likely to return (X23), and likely to recommend (X24). They want to see whether there are differences in the levels of satisfaction, likely to return, and likely to recommend between people who recall the ads and who do not recall the ads. Set the hypothesis, report the SPSS analysis findings and advise Santa Fe Grill owners about potential implications (15 pts – 10 points setting the hypothesis and running the proper analysis, 5 points for the business advise).

6.d. Santa Fe Grill owners want to find out whether their customers’ (a) likelihood to return (X23) and (b) likelihood to recommend (X24) the restaurant are different based on how far their customers travel to get to the restaurant. In other words, do statistically significant differences exist for X23 and X24 between all the distance driven customer groups, or only some? Set the hypothesis, report the SPSS analysis findings and advise Santa Fe Grill owners about potential implications (15 pts – 10 points setting the hypothesis and running the proper analysis,5 points for the business advise).

 

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Statistics case study
Paper , Order, or Assignment Requirements

Bottling Company Case Study

worth 140 points

Imagine you are a manager at a major bottling company. Customers have begun to complain that the bottles of the brand of soda produced in your company contain less than the advertised sixteen (16) ounces of product. Your boss wants to solve the problem at hand and has asked you to investigate. You have your employees pull thirty (30) bottles off the line at random from all the shifts at the bottling plant. You ask your employees to measure the amount of soda there is in each bottle. Note: Use the data set provided by your instructor to complete this assignment.

Instructional Video https://youtu.be/SVCYhNaR73E Step by step instructions

Bottle Number

Ounces

Bottle Number

Ounces

Bottle Number

Ounces

1

14.23

11

15.77

21

16.23

2

14.32

12

15.80

22

16.25

3

14.98

13

15.82

23

16.31

4

15.00

14

15.87

24

16.32

5

15.11

15

15.98

25

16.34

6

15.21

16

16.00

26

16.46

7

15.42

17

16.02

27

16.47

8

15.47

18

16.05

28

16.51

9

15.65

19

16.21

29

16.91

10

15.74

20

16.21

30

16.96

Write a two to three (2-3) page report in which you:

Calculate the mean, median, and standard deviation for ounces in the bottles.
Construct a 95% Confidence Interval for the ounces in the bottles.
Conduct a hypothesis test to verify if the claim that a bottle contains less than sixteen (16) ounces is supported. Clearly state the logic of your test, the calculations, and the conclusion of your test.
Provide the following discussion based on the conclusion of your test:
If you conclude that there are less than sixteen (16) ounces in a bottle of soda, speculate on three (3) possible causes. Next, suggest the strategies to avoid the deficit in the future.
Or

If you conclude that the claim of less soda per bottle is not supported or justified, provide a detailed explanation to your boss about the situation. Include your speculation on the reason(s) behind the claim, and recommend one (1) strategy geared toward mitigating this issue in the future.
Your assignment must follow these formatting requirements:

Be typed, double spaced, using Times New Roman font (size 12), with one-inch margins on all sides. No citations and references are required, but if you use them, they must follow APA format. Check with your professor for any additional instructions.
Include a cover page containing the title of the assignment, the student’s name, the professor’s name, the course title, and the date. The cover page and the reference page are not included in the required assignment page length.
The specific course learning outcomes associated with this assignment are:

Calculate measurements of central tendency and dispersal.
Determine confidence intervals for data.
Describe the vocabulary and principles of hypothesis testing.
Discuss application of course content to professional contexts.
Use technological tools to solve problems in statistics.
Write clearly and concisely about statistics using proper writing mechanics.

view the grading rubric for this assignment.

Points: 140
Criteria
Fair

70-79% C

Proficient

80-89% B

Exemplary

90-100% A

1. Calculate the mean, median, and standard deviation for ounces in the bottles.
Weight: 20%

Partially calculated the mean, median, and standard deviation for ounces in the bottles. Satisfactorilycalculated the mean, median, and standard deviation for ounces in the bottles. Thoroughly calculated the mean, median, and standard deviation for ounces in the bottles.
2. Construct a 95% Confidence Interval for the ounces in the bottles.
Weight: 25%

Partially constructed a 95% Confidence Interval for the ounces in the bottles. Satisfactorilyconstructed a 95% Confidence Interval for the ounces in the bottles. Thoroughlyconstructed a 95% Confidence Interval for the ounces in the bottles.
3. Conduct a hypothesis test to verify if the claim that a bottle contains less than sixteen (16) ounces is supported.Clearly state the logic of your test, the calculations, and the conclusion of your test.
Weight: 30%

Partially conducted a hypothesis test to verify if the claim that a bottle contains less than sixteen (16) ounces is supported. Partially stated the logic of your test, the calculations, and the conclusion of your test. Satisfactorilyconducted a hypothesis test to verify if the claim that a bottle contains less than sixteen (16) ounces is supported. Satisfactorily stated the logic of your test, the calculations, and the conclusion of your test. Thoroughly conducted a hypothesis test to verify if the claim that a bottle contains less than sixteen (16) ounces is supported. Thoroughly stated the logic of your test, the calculations, and the conclusion of your test.
4a. If you conclude that there are less than sixteen (16) ounces in a bottle of soda, speculate on three (3) possible causes. Next, suggest the strategies to avoid the deficit in the future.

Or

4b. If you conclude that the claim of less soda per bottle is not supported or justified, provide a detailed explanation to your boss about the situation. Include your speculation on the reason(s) behind the claim, and recommend one (1) strategy geared toward mitigating this issue in the future.

Weight: 15%

Partially speculated on three (3) possible causes. Partially suggested the strategies to avoid the deficit in the future.

Or

Partially provided a detailed explanation to your boss about the situation. Partially included your speculation on the reason(s) behind the claim, and partially recommended one (1) strategy geared toward mitigating this issue in the future.

Satisfactorily speculated on three (3) possible causes. Satisfactorily suggested the strategies to avoid the deficit in the future.

Or

Satisfactorily provided a detailed explanation to your boss about the situation. Satisfactorily included your speculation on the reason(s) behind the claim, and satisfactorily recommended one (1) strategy geared toward mitigating this issue in the future.

Thoroughlyspeculated on three (3) possible causes. Thoroughlysuggested the strategies to avoid the deficit in the future.

Or

Thoroughlyprovided a detailed explanation to your boss about the situation. Thoroughlyincluded your speculation on the reason(s) behind the claim, and thoroughlyrecommended one (1) strategy geared toward mitigating this issue in the future.

5. Writing / Support for ideas
Weight: 5%

Partially uses reasons and evidence that logically support ideas. Mostly uses reasons and evidence that logically support ideas. Consistently uses reasons and evidence that logically support ideas.
6. Writing / Grammar and mechanics
Weight: 5%

Partially free of errors in grammar, spelling, and punctuation. Mostly free of errors in grammar, spelling, and punctuation. Free of errors in grammar, spelling, and punctuation.

 

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