Biostats part 2

Question 1

Proportion Example:
n=200 patients
X= 90 adverse drug reactions
what is the estimated proportion who experiences an adverse drug reaction:

Answer 1

p (hat) = 90/200 = 0.45 or 45%

hat means estimate

Question 2

In the proportion example if a larger number of patients would have been studied would there be a different answer?

Answer 2

yes, n=200 leads to uncertainty in the answer

Question 3

How is the standard error (SE (p hat)) of a sample proportion calculated?

Answer 3

SE (p hat) = sq root of p x 1-p / n

Question 4

95% CI for proportion example:
n=200 patients
X =90 adverse drug reations
p (hat) = 0.45 (calculated previously)

Answer 4

0.45 +- 2 x sq.root 0.45 x 0.55/200
0.45 +- 2 x 0.035
0.45 +- 0.07
95% CI is (.38-.52)