AP Statistics Notes: Unit 7

Intervals for Population Proportion:

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

• Confidence Level: the probability that the value of a parameter falls within a specified range of values

• Conditions for constructing a confidence interval for the parameter: SRS, 10% Rule, and Large Counts

• Interpret values example: We are __% confident that the confidence interval captures the proportion of red beads between __and___.

• Confidence interval formula:

  

Determining Sample Size:

• Sampling Variability: Larger samples give smaller spreads while smaller samples give larger spreads

• Determining Sample Size Formula:

T* Intervals vs. Z* Intervals

• When a sample size is 30+ t* interval is used

• When a sample size below 30 z* interval is used

• T* formula: x̄ +- t* (sx/√n)

• Z* formula: z*+-p^√p^(1-p^)/n