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	46
hot air	10	42	52
	29	69	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 illness

Halt There is an association between drying choice and illness

1- TRUE OR FALSE

2- What is your estimate of the prevalence/incidence of illness in this population (enter as a proportion 0.000 to 1.000)

3-

expected values
	sick	not sick
paper	a	b
hot air	c	d

complete the expected values a=

4- complete the expected values b=

5-complete the expected values c =

6- complete the expected values d =

7-complete the expected values- Number of Degrees of Freedom for this 2x2 table

8-What is the calculated value of Chi Square (without continuity correction) for these findings

9-Based on this result you cannot reject your null hypothesis.- TRUE OR FALSE

10- Based on this result you can reject your null hypothesis that there is no association and accept your alternative hypothesis that there is an association between drying technique and respiratory illness.- TRUE OR FALSE

11-

observed values	sick	not sick
paper	19	27	46
hot air	10	42	52
	29	69	98

Calculate risk of becoming ill if you use paper towels for hand drying and your risk of becoming ill if you use hot air.

Enter the Relative Risk for these exposures below (aka Risk Ratio)

12-

observed values	sick	not sick
paper	19	27	46
hot air	10	42	52
	29	69	98

Calculate odds of becoming ill if you use paper towels for hand drying and your risk of becoming ill if you use hot air.

Enter the Odds Ratio for these exposures below

13-

Repeat the Chi Square analysis and odds ratio calculation using SPSS (file Hotairvpaper.sav)

Which of the following is an appropriate hull and alternative hypothesis for the odds of becoming ill based on hand drying choice.

		Hnull OR = 0 Halt OR =/= 0
		Hnull OR = 1 Halt OR =/= 1
		Hnull OR > 1 Halt OR < 1
		None of the above

14- Based on the confidence interval for the Odds Ratio calculated using SPSS

You reject the null hypothesis and accept the alternative hypothesis, that there is an association between hand drying choice and illness.

TRUE OR FALSE