STATS 250 Lecture 2: Sampling, Surveys, and Gathering Useful Data

• School: U of M
• Department: Statistics
• Course: STATS 250
• Professor: Brenda Gunderson

Document Summary

Stats 250: introduction to statistics - lecture 2: sampling, surveys, and gathering. When mean is used to measure center, the most common measure of spread is the standard deviation. A measure of the spread of the observations from the mean. A kind of average distance of the observations from the mean. Defined as the square root of the average of the squared deviations of the observations from the mean. When s = 0, there is no spread and all observations are the same. When s > 0, there is more spread/variability. Therefore, use the standard deviation for reasonably symmetric, bell- shaped data sets. The symbols and the formulas for the mean and standard deviation for a population and for a sample from a population are different. A population mean is represented by the greek letter mu ( ) while a sample.