Question

A research study aimed at evaluating the efficacy of aspirin in the prevention of thrombosis among patients under dialysis gave the following results (please use the results to answer questions 11 through 13): Placebo Group Aspirin Group Total Development of thrombosis Yes No 18 7 6 12 24 19 Total 25 18 43 What is the correct null (HO) hypothesis? HO: two groups proportions of development of thrombosis cannot be compared nt of HO: two groups have significantly different proportions of de thrombosis HO: two groups have the same proportions of development of thrombosis OHO: Placebo group have higher proportions of development of thrombosis

Answer 1

Answer: Option C

We want to test whether aspirin has significant impact on patients under dialysis to prevent them from thrombosis

Hence, we want to test whether two groups i.e. one with medicine and other with no medicine have same risk of development of thrombosis.

Correct Null Hypothesis is

Ho: Two groups have the same proportions of development of thrombosis

H1: Two groups have the different proportions of development of thrombosis

Answer: Option B

Here, we want to test whether there is association between effect of aspirin and development of thrombosis

i.e. we want to find association between two categorical variables, group type (Categories: Placebo Group, Aspirin Group) and whether patients suffers from development of thrombosis (Categories: Yes, No)

To test association between two or more categorical variables, we use Chi-Square Test

Answer: Option A, B, D

Reject null hypothesis with alpha = 0.1

Reject null hypothesis with alpha = 0.05

Fail to reject null hypothesis with alpha = 0.001

Alpha	p-value	Criterion	Decision
0.1	0.012	p-value(0.012)<0.1	Reject Ho at alpha = 0.1
0.05	0.012	p-value(0.012)<0.05	Reject Ho at alpha = 0.05
0.01	0.012	p-value(0.012)>0.01	Do Not Reject Ho at alpha = 0.01
0.001	0.012	p-value(0.012)>0.001	Do Not Reject Ho at alpha = 0.001