Question

A doctor wants to estimate the mean HDL cholesterol of all 20- to 29-year-old females. How many subjects are needed to estimate the mean HDL cholesterol within 3 points with 99 % confidence assuming s equals 11.5 based on earlier studies? Suppose the doctor would be content with 90 % confidence. How does the decrease in confidence affect the sample size required?

LOADING... Click the icon to view a partial table of critical values. ( 0.05 1.645)

A 99% confidence level requires how many subjects?

Level of​ Confidence,	​(1minus−alphaα​)times•​100%	Area in Each​ Tail, StartFraction alpha Over 2 EndFractionα2	Critical​ Value, z Subscript alpha divided by 2zα/2
​90%		0.05		1.645
​95%		0.025		1.96
​99%		0.005		2.575

Answer 1