1. Statistics 200 Objectives:
Lecture #22 Thursday, November 3, 2016
Textbook: through 10.4, 11.1 though 11.5
Objectives:
• Identify the correct CI approach for all the various situations we have studied.
• Construct and interpret any CI correctly.

2. Confidence Interval Formula: Case #1
sample estimate ± (multiplier × standard error)
Which situation characterizes case #1?
single proportion
single mean
difference of two proportions
difference of two means
mean difference of paired observations
Textbook reference: Section 10.2

3. Confidence Interval Formula: Case #2
sample estimate ± (multiplier × standard error)
Which situation characterizes case #2?
single proportion
single mean
difference of two proportions
difference of two means
mean difference of paired observations
Textbook reference: Section 10.3

4. Confidence Interval Formula: Case #3
sample estimate ± (multiplier × standard error)
Which situation characterizes case #3?
single proportion
single mean
difference of two proportions
difference of two means
mean difference of paired observations
Textbook reference: Section 11.2

5. Confidence Interval Formula: Case #4
sample estimate ± (multiplier × standard error)
Which situation characterizes case #4?
single proportion
single mean
difference of two proportions
difference of two means
mean difference of paired observations
Textbook reference: Section 11.3

6. Confidence Interval Formula: Case #5
sample estimate ± (multiplier × standard error)
Which situation characterizes case #5?
single proportion
single mean
difference of two proportions
difference of two means
mean difference of paired observations
Textbook reference: Section 11.4

7. About the multiplier in a CI:
sample estimate ± (multiplier × standard error)
Suppose the confidence level is 95%, and study the picture.
Which percentile is the z* or t* value?
(Hint: It’s NOT the 95th or 5th percentile!)

8. About the multiplier in a CI:
sample estimate ± (multiplier × standard error)
Suppose the confidence level is 98%.
Which percentile is the z* or t* value?
95th
96th
97th
98th
99th

9. About the multiplier in a CI:
sample estimate ± (multiplier × standard error)
Should you use a z* or a t* multiplier?
One proportion or diff of two proportions: z*
One mean or diff of two means, σ known: z*
One mean or diff of two means, σ unknown: t*
(mean of paired differences: same as one mean)

10. Some Minitab output:
Descriptive Statistics: tvhours
Variable owngun N Mean SE Mean StDev No
Yes
Which is the correct confidence interval formula for this situation?

11. Some Minitab output:
sex Count
Female
Male N=
Which is the correct confidence interval formula for this situation?

12. Some Minitab output:
Variable N Mean SE Mean StDev
GPAgoal
GPApred
GoalMinusPred
Which is the correct confidence interval formula for this situation?

13. Some Minitab output:
Descriptive Statistics: PrtyMnth
Variable Gender N Mean SE Mean StDev
Female
Male
Which is the correct confidence interval formula for this situation?

14. Some Minitab output:
Rows: HaveDog Columns: HaveCat
No Yes All No
Yes
All
Which is the correct confidence interval formula for this situation?

15. Some Minitab output:
Variable N Mean SE Mean StDev
StudHrWk
Which is the correct confidence interval formula for this situation?

16. If you understand today’s lecture…
10.70, 10.71, 10.75, 10.85, 11.68, 11.69, 11.74, 11.75, 11.81, 11.83
Objectives:
• Identify the correct CI approach for all the various situations we have studied.
• Construct and interpret any CI correctly.