Statistical procedures for missing data have vastly improved, yet misconception and unsound practice still abound. The authors frame the missing-data problem, review methods, offer advice, and raise issues that remain unresolved.

Correspondence concerning this article should be addressed to Christina M. Leclerc, Department of Psychology, Boston College, McGuinn Hall, Room 512, 140 Commonwealth Avenue, Chestnut Hill, MA 02467. Email: christina.leclerc.1@bc.edu 11353-349

Nine individuals were subsequently invited to join and all agreed. These were Leona Aiken, Mark Appelbaum, Gwyneth Boodoo, David A. Kenny, Helena Kraemer, Donald Rubin, Bruce Thompson, Howard Wainer, and Leland Wilkinson.

This PDF is a reprint of a book chapter that considers problems with null hypothesis significance testing.

Wider use in psychology of confidence intervals (CIs), especially as error bars in figures, is a desirable development. However, psychologists seldom use CIs and may not understand them well.

Supplemental test questions for Mastering APA Style: Instructor's Resource Guide, Sixth Edition. This is a PDF download.