Question

3) In a recent survey by Consumer Reports, 32% go to Urgent Care Clinics for non-emergency care when their regular doctor is not available. Assume a sampling error of ± 3%.

Source: Consumer Reports, “Where Do You Go For Non-emergency Care When Your Regular Doctor Is Not Available”, p. 41, May 2020.

If you want 99% confidence, how large a sample proportion is needed? _________________

Answer 1

Solution,

Given that,

= 0.32

1 - = 1 - 0.32 = 0.68

margin of error = E = 0.03

At 99% confidence level

= 1 - 99%

= 1 - 0.99 =0.01

/2 = 0.005

Z/2 = Z0.005  = 2.576

sample size = n = (Z / 2 / E )2 * * (1 - )

= (2.576 / 0.03 )2 * 0.32 * 0.68

= 1604.38

sample size = n = 1605