1. Estimating Ability with Confidence Intervals

2. Vocabulary used in this Lesson
Margin of Error
Confidence Interval
Sample Mean
Standard Deviation

3. Confidence Interval
An interval of plausible values where an Data point may fall
An interval is better than single value because of chances of accuracy have increased

4. 95% Confidence Intervals Three very common intervals: Interval Z-score
90%
95%
99%
Interval Z-score

5. Interpreting Confidence Intervals
About 95% of all the intervals we construct will contain the athlete’s ability
“We are 95% confident that the interval of plausible values from _________ to _________ contains ____________’s ability ___________________________”

6. General Form for Confidence Interval

7. OR Margin of Error Upper Endpoint – Observed Performance
Observed Performance – Lower Endpoint

8. Calculating a Confidence Interval for a Proportion

9. Calculating a Confidence Interval for a mean

10. Lawn Weeds
A survey of 1898 adults with lawns conducted by Harris Interactive Poll found that 45% of the adults said that dandelions were the toughest weeds to control in their yards. Find the 95% confidence interval of the true proportion who said that dandelions were the toughest weeds to control in their yards.

11. Lawn Weeds
Hence you can say with ______ confidence that the true percentage of adults who consider dandelions the toughest weeds to control in their lawns is between ___________ and _________.

12. Perry Como Fans
Fifty-six percent of respondents to an online poll said that they were Perry Como fans. If 982 randomly selected people responded to this poll, what is the true proportion of all local residents who are Perry Como fans? Estimate at the 95% confidence level.

13. Perry Como
Hence you can say with ______ confidence that the true percentage of________________________________________________________________is between ___________ and _________.

14. Continue working on examples

15. KNOCKOUT

16. 1. What are the three most common confidence intervals?
10%, 100% and 1000%
90%, 95% and 99%
80%, 90% and 100%
85%, 95% and 100%

17. 2. What is the only confidence interval we deal with in this course?
100%
99%
95%
90%

18. 3. What is the meaning of 𝑝̂?
Ability (true proportion of successes)
Performance (observed proportion of successes)
Sample size
Confidence Interval

19. 4. What is the meaning of 𝑝? Ability (true proportion of successes)
Performance (observed proportion of successes)
Sample size
Confidence Interval