Statistical Assignment – Case Study

Pilot Study

Objective:

To examine the relationship between serum vitamin D levels and obesity in adults.

Your boss, the study’s investigator, has the primary hypothesis that serum vitamin D levels are significantly lower in obese adults compared to adults of normal weight.

A secondary hypothesis being tested in the study is that most of the adults that are evaluated will be considered vitamin D deficient.

Definitions:

Normal value for serum 25- hydroxyvitamin D (25-OHD) levels is > 30 ng/mL.

Deficiency is indicated at levels < 30 ng/mL.

The information that you collect is the following:

1. gender
2. age (in years)
3. weight (in kg)
4. height (in cm)
5. 25-hydroxyvitamin D levels ( in ng/ml)
6. 1, 25-dihydroxyvitamin D levels (in pg/ml)
7. blood glucose level (in mg/dL)
8. supplement usage (either yes or no)
9. sunscreen usage (either yes or no)
10. site that data was collected from (named A through C)

The data collected is found in the Excel spreadsheet, which is provided to you. Each participant is assigned an ID number, found in the spreadsheet. Your boss wants to the use the pilot study data to apply for an NIH grant, and she asks you to give her a report on the findings. You work closely with a statistician, who will run the appropriate statistical tests

STUDENT NAME: LESLIE MALACHI

Answer the following questions.

1. What other information can you generate with the data that you have collected? How wouldyou determine or calculate this new data? (1 pt)
2. What are some of the relationships or differences that you would like to examine with this data? Besides the primary and secondary hypotheses of the pilot study, n ame at least 4 relationships or differences. (4 pt)
3. Generate hypotheses:

1. What is the study investigator’s primary working hypothe sis in this study? What are the appropriate null and alternate hypotheses to address the working h ypothesis with statistics (i.e. statistical hypotheses)? (5pt)

4. Describe your quantitative data:

Using a calculator or MS Excel, determine the mean, median,and mode of each quantitative variable in the dataset. Create a table (using MS Word) to summarize thisdata. If there is none for any mean, median or mode, indicate this by "N/A." Round calculated values tothe closest hundredths place (10pt).

5. Determine the distribution of your data: look at the provided skewness tests of body weight, 25OHD, 1,25-dihydroxyvitamin D, glucose levels, and height; are these variables normally or skewed indistribution? (10pt)

6. From #5, what type (parametric vs. nonparametric) of statistical tests are appropriate using the variables listed? Why does determining the type of statistical test matter? (6 pt)

7. Test the hypotheses: Using the statistical printouts provided, indic ate the appropriate statistical test for the variables indicated, and interpret the statistical outcome for each below (10pt):

1. T-test OR Mann-Whitney test*:
   Examine 25OHD levels of overweight subjects compared to levels in normal weight subjects
2. Chi-square (no non-parametric test equivale nt): Examine the number of subjects that are considered vitamin D deficient compared to those who aren’t; interpret the statistical outcome.
3. Pe arson or Spearman* Correlation: Examine the relationship between 25OHD and body weight
4. Analysis of Variance (ANOVA) or Kruskal-Wallis test: Examine 25OHD between locations A, B, and C

8. Display the results: Keep in the mind the criteria for a good graph or table, as given in the coursematerials.

1. Display the mean 25OHD by location by creating a bar graph (u sing MS Excel). Make one conclusion based upon this figure. (5 pt)
2. Using the data provided, create a table (using MS Word) whi ch summarizes the following data as the mean ± standard deviation: 25OHD, % o f supplement usage, % sunscreen usage, mean age, and mean BMI by gender. Round mean values to the closest hundredth. Make one conclusion based upon the data in this table. (5 pt)

9. List 2 other hypotheses or comparisons that you would like to look at if you were to continue your analyses. Provide your rationale for these comparisons. (4 pt)

Price: $26.8

Solution: The downloadable solution consists of 8 pages, 1880 words and 1 charts.
Deliverable: Word Document