Question

Define confidence interval and degree of confidence. Provide at least one example of a confidence interval and interpret the result.

Answer 1

Confidence Interval is defined as a range of values so defined that there is a specified probability that the value of a parameter lies within it.

Degree of Confidence is defined as the probability that the Confidence Interval captures the true population parameter.

Example of a confidence interval:

Consider height of Sample of n = 40 men.

Let Sample mean = = 175 cm

Let Population SD = = 20 cm

SE = /

= 20/

= 3.1523

Let

= 0.05

From Table, critical values of Z = 1.96

So,

Confidence Interval:

175 (1.96 X 3.1523)

= 175 6.1981Done

= ( 168.8018 ,181.1981)

Interpretation:

The 95% Confidence Interval ( 168.8018 ,181.1981) is a range of values so defined that there is a 95% probability that the value of a parameter lies within it.