Samples, Surveys, and Results UNIT SELF-TEST QUESTIONS Statistics and Data Analysis 2 LAST UNIT 1 CURRENT UNIT CURRENT UNIT 3 NEXT UNIT Correlation and Regressions Samples, Surveys, and Results Hypothesis Testing BIAS Volunteer Convenience Sample Frame Undercoverage Non- Respondents 4 Sampling Methods Confidence Intervals is about... Asking Questions Slope Triangles Building a Simulation: 6 steps Standard Deviation for Proportions Sample Size Sample Proportion How can you sample badly? What are the steps for designing a simulation? What the different sampling methods? How do you use the standard 68-95-99 rule to determine the confidence interval? What two things do the confidence interval tell you? How do you find the standard deviation for a sample proportion? Is the margin of error always the same? UNIT SELF-TEST QUESTIONS

Notes Making a Simulation Steps for Simulation What is the component to be repeated? How will you model the outcome? How will you simulate the trial? State the response variable. Run the trials. State conclusion.

Sample Size Population Sample Size 100 80 500 217 1,000 285 5,000 357 10,000 370 50,000 381 1,000,000 384 Sample size is how many respondents you need to make good inference Depends on: margin of error you want Confidence Interval you want How much money and time you have Common Equation for sample size: n*p > 10 and n*q > 10 n = sample size p = mean proportion of the sampling distribution q = 1 - p

Stratified Sample Break the population into groups then take random samples from each group

Simple Random Sample SRS a group of subjects (a sample) is selected from a larger group (a population). Each individual is chosen by a random process (random number generator or a random number table) Every type of group in the population is represented

Systematic Sample Use a pattern to collect samples (every 4th person who walks by)

Notation Name Statistic Parameter Mean μ (pronounced “meeoo”) Standard Deviation s σ (sigma) Correlation r ρ (rho) Regression Coefficient b β (beta) Proportion p