Download Chapter 9 Key Ideas and Words

Chapter 9
Key Ideas and Words
Section 9.1
 Point estimate
o statistics vs. parameter
𝑥
o point estimate for population proportion p is ̂𝑝 = 𝑛
o p may also represent a probability of a binomial distribution, such as p=0.5 for a fair
coin.
 Confidence interval for an unknown parameter
 Margin of error
 Interpretation of what is meant by being “95%” confident (think simulations
 Formula for confidence interval for population proportion, p.
 Know z-multipliers for 90%, 95%, and 99% confidence intervals.
 Requirements: Minimum sample size and sample size very small relative to population size.
o np(1-p) >= 10
o n <= 0.05N, N=population size
 Calculating sample size to obtained desired margin of error E.
o Using educated guess for population proportion.
o Using p=0.5 for conservative (large) sample size.
o Round up to nearest integer.
Section 9.2
 Point estimate for population mean is the sample mean
 Distribution of z-score for sample mean using sample standard deviation, S, instead of
population standard deviation, 𝜎.
 Student’s t-distribution
o Degrees-of-freedom
o t-table
 t-distribution vs. standard normal (Z) distribution
 Formula for confidence interval for population mean 𝜇
 How to calculate approximate sample size to get desired margin of error E.
o Note: This calculated n is likely too small because z-value < t-value