Chapter 8: Interval Estimation

Question 1

Confidence Interval

Answer 1

a range of values constructed around a sample statistic that estimates the parameter

AKA: Interval Estimate

Question 2

Confidence Limit

Answer 2

Lower and upper bounds of a confidence interval

Question 3

3 -Parts of a Confidence Interval

Answer 3

1. Confidence Level (%)
2. Point Estimate
3. Margin of Error

Question 4

Margin of Error

Answer 4

The largest possible distance between the statistic and the parameter

(critical value)(standard error)

Question 5

Confidence Level

Answer 5

the percentage of intervals that will contain the parameter given a statistic

Question 6

Confidence Coefficient

Answer 6

The confidence level as a proportion

Question 7

⍺

Answer 7

• the level of error you are willing to accept
• the area in the tails

AKA: Significance level

Question 8

As ⍺ gets smaller →

Answer 8

it becomes more “strict” or “stringent” and the “specificity” of the interval decreases

Question 9

Critical Value

Answer 9

z-scores that correlate to the confidence limits

Question 10

Critical Probability

Answer 10

Area below a z-score

Question 11

Critical Value for a 99% CI

Answer 11

⍺ = 0.01

CV = +/- 2.576

Question 12

Estimating Sample Size Without σ

Answer 12

• s
• range / 4

Question 13

T-Distribution v. Z-Distribution (3)

Answer 13

• variance of the t-distribution > 1
• t-distribution is a family of curves
• as the sample size increases, the t-distribution approaches the z-distribution

Question 14

Sample Size and Critical Values (t-table)

Answer 14

as the sample size increases → the critical value decreases → margin of error decreases → CI becomes smaller

Question 15

Degrees of Freedom

Answer 15

n-1

Question 16

p*

Answer 16

• sample proportion from previous studies
• sample proportion from a pilot study
• planning value = 0.5