Question 306102
A clinical trial is conducted comparing a new pain reliever for arthritis to a placebo.  Participants are randomly assigned to receive the new treatment or a placebo.  The outcome is pain relief within 30 minutes.  The data are shown in table 6-8


		         Pain relief	     no Pain relief	
New medication    	      44		    76
Placebo 	              21	            99 	
    
a. Generate a 95% confidence interval for the proportion of patients on the new medication who report pain relief.
sample proportion: 65/240 = 0.27
standard error = E = 1.96*sqrt[0.27*0.73/240] = 0.056
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95% CI: 0.27-0.056 < p < 0.27+0.056
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b. Generate a 95 % confidence interval for the difference in proportions of patients who report pain relief.
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sample proportion: (44/120)-(21/120 = 23/120 = 0.19
standard error: 1.96*sqrt(0.19*0.81/120) = 0.07
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95% CI: 0.19-0.07 < P < 0.19+0.07
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Cheers,
Stan H.