STAT 250 - Problem set 4 part 1 and 2. Question and Answer

STAT 250 - Problem set 4 part 1 and 2. Question and Answer Problem set 4 part1 (Ch 18 and 13) Two-way tables and ANOVA Name 1. A researcher interested in the relationship between BMI (kg/m2) and hypertension has decided to categorize BMI into four classes based on national recommendations. The researcher gathered secondary data from various hospital records and selected 409 cases of hypertension matched to hypertensive-free controls on a variety of demographic characteristics including age, sex, education, and socio-economic status. The cases and controls were then categorized based on their BMI at a weigh in after signing informed consent. The following table summarizes the relationship between the outcome and exposure variables. Hypertensive Non-Hypertensive Total BMI Cat I Underweight (18.5) 33 54 87 BMI Cat II Normal (18.5, 24.9) 83 278 361 BMI Cat III Overweight (25, 29.9) 151 98 249 BMI Cat IV Obese (30+) 142 26 168 Total 409 456 865 A) What type of study is being conducted? Case-Control Study B) Perform a formal statistical test to determine if there is a difference in risk for hypertension between BMI categories. Write out your null and alternative hypotheses, and interpret your results at the alpha level of 0.05. It a xi-square test and it rejects the Ho and there is no association between category of BMI and hypertensive status. C) Calculate the appropriate risk measure for hypertension risk based on exposure categories II, III, and IV using category I as the non-exposed group. 4 to 1= 8.952 D) Based on your results in B and C, does there appear to be one group that carries the highest risk for hypertension? The hypertension is the highest in the fourth category compared to the obese participants. Ans: A) Case-Control Study B) Xi-square test Ho: no association between BMI category and hypertensive status in the source population Ha: association exists between the variables. Xi-Square stat=199.814 3 df Pvalue ~0 Reject the Ho that there is no association between category of BMI and hypertensive status. C) ORi(2 to 1)=.488, ORii(3-1)=2.524, ORiii(4 to 1)= 8.952 D) Based on this analysis, it seems that the risk for hypertension is highest among the fourth