Department of Statistics Seminar
North Carolina State University

presents

Dr. Alan Agresti

University of Florida

Improving Confidence Intervals for Proportions, Differences
of Proportions, and Odds Ratios

ABSTRACT

`Exact,' small-sample methods for categorical data are exact in terms of using probability distributions that do not depend on unknown parameters. However, they are conservative inferentially, having actual error probabilities for tests and confidence intervals that are bounded above by the nominal level. We examine the conservatism for interval estimation and suggest ways of reducing it, illustrating for the binomial proportion, the difference between two proportions, and the odds ratio. We also summarize simple ways of adjusting standard large-sample confidence intervals to improve dramatically their small-sample performance.

Friday, January 24, 2003

3:35 - 4:35 pm

206 Cox Hall

Refreshments will be served on the second floor of Dabney Hall (left of Room 222) at 3:00 pm.