hw 7

Hoja1

HW 7 ANSWER SHEET
Task 1: 2-way frequency table (contingency table)
		RISK: Hypertension
		yes	no	row marginals
RISK FACTOR:	yes	14	7	21
Obesity	no	12	27	39	cross check
	column marginals	26	34	60	60
TASK 2: MINITAB output for chi-square test for association and Fisher's exact test
Chi-Square Test
	Chi-Square	DF	P-Value
Pearson	7.163	1	0.007
Likelihood Ratio	7.229	1	0.007
Fisher’s Exact Test
P-Value	0.0131801
ANSWER:
Task 3: Risk, relative risk, odds and odds ratio
A: Risk (= row proportion)
Risk of developing hypertension for obese subjects				0.667
Risk of developing hypertension for non-obese subjects				0.308
B: Relative risk (risk ratio or ratio of row proportions)				2.17
C: Odds to develop hypertension (proportion of hypertension/no hypertension)
For obese people				2.000
for nonobese people				0.444
D: Odds ratio				4.5
Task 4: Confidence intervals for risk and odds ratios
(output from https://statpages.info/ctab2x2.html)

Both the Pearson chi-square test and Fisher's Exact test show that the two variables (obesity and hypertension) are associated, because both p-values are below the selected significance level of 0.05. The null hypothesis is rejected.

The risk of developing hypertension is 2.17 fold higher for obese people as compared to nonobese people (95% CI: 1.14 - 3.71).

The odds of developing hypertension are 4.5 times higher for obese people as compared to nonobese people (95% CI 1.4 - 14.0).