Margin of Error S-IC.4 Use data from a sample survey to estimate a population mean or proportion; develop a margin of error through the use of simulation models for random sampling. S-IC.5 Use data from a randomized experiment to compare two treatments; use simulations to decide if differences between parameters are significant. S-IC.6 Evaluate reports based on data.

Vocabulary  Population: what you are trying to gain knowledge about  Sample: part of the population used to gain knowledge  Parameter: a descriptive measurement of the population  Statistic: a numerical measurement of the sample (an estimate for the parameter)

Sample Distribution

Margin of Error  Margin of Error: a numerical way to determine the difference between how a sample and the population responds  Range of values above and below the sample statistic  Used in reporting the results of a statistical study

Confidence Intervals  The margin of error should be qualified by a confidence interval  A range of values in which there is a specified probability that the value of a parameter lies within it  EX: A pollster might report that 50% of voters will choose the Democratic candidate. To indicate the quality of the survey result, the pollster might add that the margin of error is +5%, with a confidence level of 90%.

Determining z* value  The confidence percentage determines which value of z* to use

Calculating Margin of Error

Examples people were asked if they like football. 38% responded yes. Calculate the margin of error. 2. In a recent survey, 934 people out of 2150 stated that they read the newspaper every day. Construct the confidence interval with 95% confidence.

Calculating Margin of Error

Examples