Question

Surgical complications: A medical researcher wants to construct a 98% confidence interval for the proportion of knee replacement surgeries that result in complications.

) Estimate the sample size needed if no estimate of

p

is available.

A sample of __operations is needed to obtain a 98%confidence interval with a margin of error of 0.08 when no estimate of p is available.

Answer 1

Solution :

Given that,

= 0.5

1 - = 0.5

margin of error = E = 0.08

At 98% confidence level the z is,

= 1 - 98%

= 1 - 0.98 = 0.02

/2 = 0.01

Z_/2 = 2.326 ( Using z table )

Sample size = n = (Z_/2 / E)² * * (1 - )

= (2.326 / 0.08)² * 0.5 * 0.5

=195