In: Statistics and Probability
The ICU-Admissions dataset includes a variable indicating the age of the patient. Find and interpret a 90% confidence interval for mean age of ICU patients using the facts that, in the sample, the mean is 55.75 years and the standard error for such means is SE = 1.64. The sample size of 100 is large enough to use a normal distribution
Solution :
Given that,
Point estimate = sample mean = = 55.75
SE =1.64
Sample size = n =100
At 90% confidence level the z is
= 1 - 90% = 1 - 0.90 = 0.1
/ 2 = 0.1 / 2 = 0.05
Z/2 = Z0.05 = 1.645 ( Using z table )
Margin of error = E = Z/2
* (
/n)
=Z/2
* SE
= 1.645 * 1.64
= 2.7
At 90% confidence interval
is,
- E <
<
+ E
55.75 - 2.7 <
< 55.75+ 2.7
53.05 <
< 58.45
( 53.05, 58.45)