Field Research Methods. Lecture 4: Sampling & Sampling Error. Edmund Malesky, Ph.D., UCSD. Probability Sampling. Each element has a known, nonzero chance of being included in the sample. Selection bias is avoided
Sampling & Sampling Error
Edmund Malesky, Ph.D., UCSD
Simple Random Sampling: Will give me the percentage balls of a certain color (plus/minus 3%)
If I want to be more certain, I stratify and randomly sample within category
If you are interested in a proportion of the population substitute P(1-P) for S.
A joke from Joe Klein: “Prime Minister Ehud Olmert is testing the limits of the possible: in a recent poll by a local television station, he had a favorable rating of 3%. Given the poll's margin of error, it was possible Olmert had no support beyond his extended family."
Click here for on-line version