In: Statistics and Probability
A physician with a practice is currently serving 300 patients. The physician would like to administer a survey to his patients to measure their satisfaction level with his practice. A random sample of 24 patients had an average satisfaction score of 8.1 on a scale of 1-10. The sample standard deviation was 1.5. Complete parts a and b below.
a. Construct a 99% confidence interval to estimate the average satisfaction score for the physician's practice.
The 99% confidence interval to estimate the average satisfaction score (____,____)
Solution :
Given that,
= 8.1
s = 1.5
n = 24
Degrees of freedom = df = n - 1 = 24- 1 = 23
At 99% confidence level the t is ,
= 1 - 99% = 1 - 0.99 = 0.01
/ 2 = 0.01 / 2 = 0.005
t /2,df = t0.005,23 =2.807
Margin of error = E = t/2,df * (s /n)
= 2.807 * (1.5 / 24)
= 0.86
Margin of error = 0.86
The 99% confidence interval estimate of the population mean is,
- E < < + E
8.1 - 0.86 < < 8.1 + 0.86
7.24 < < 8.96
(7.24, 8.96 )