Question

You wish to examine whether hot air hand blowers or paper in a medical facility have an effect on the rate of respiratory incidence. You follow 98 health care workers in primary care clinic during flu season. You observe the following incidence of respiratory disease and preferred method of hand drying. 46 workers preferred paper for hand drying, 52 preferred hot air blowers. During the study period 29 of the 98 workers experienced a respiratory illness.

OBSERVED VALUES Sick Not Sick
Paper 19 27 49
HotAir 10 42 52
29 68 98
Your null and alternative hypothesis for the Chi Square test comparing the exposure (air vs paper) and outcome (ill or not ill is Hnull There is no association between the drying choice and ilness Halt There is an association between drying choice and illness
a.True
b. False

Answer 1

There is an association between drying choice and illness

a.True

Explanation:

H_0: There is no association between the drying choice and ilness

H_a: There is an association between drying choice and illness

(Two tailed chi square test)

Observations are given as per the following table

Observed

Sick Not sick

Paper 19 27 46

Hot air 10 42 52

29 69 98

Expected row total*col total/grand total

Paper 13.6122449 32.3877551 46

Hot air 15.3877551 36.6122449 52

29 69 98

Chi square =(observed-expected)^2/Expected

Paper 2.132484778 0.896261718 3.028746496

Hot air 1.886428842 0.792846905 2.679275747

4.01891362 1.689108623 5.708022243

Thus chi square = 5.708

degrees of freedom = (r-1)(c-1) = 1

p value = 0.0167

Since p <0.05 our alpha we reject null hypothesis

At 5% significance level, we can say

There is an association between drying choice and illness

a.True