5.1 logic of confidence intervals (3)

CI level = (upper confidence limit, lower confidence limit)

confidence interval formula

1. confidence region

2. significance region

3. critical values

three parts of a confidence interval:
1.
2.
3.

confidence region

the middle body area of a schematic curve for a confidence interval

significance region

the two tail areas of a schematic curve for a confidence interval

critical values

a pair of values (z score or t score) that separate the confidence region from the significance region

margin of error

one half of the spread of a confidence interval, expressed in x values

confidence level gets bigger and sample size gets smaller

if interval width gets wider, _______

inside the confidence interval

likely a probable value for the population mean

outside the confidence interval

an unreasonable value for the population mean

confidence level

the size of the middle confidence region, reflecting how often the method yields a correct result

significance level

the combined size of the two wail regions, representing the expected failure rate due to sample randomness (a = 1 - CL)

1. identify a, n, x, or st dev

2. use a and a schematic curve to find critical values

3. compute the interval

4. conclude the values inside the interval are reasonable for the parameter

solve confidence interval:
1.
2.
3.
4.