This chapter describes a general approach to handling missing data in psychological research. It provides a theoretical background in readable, nontechnical fashion. Our overall goal was to give practical, usable advice, rather than to give a detailed statistical treatment of issues surrounding analysis of incomplete data. We give an overview of the older, unacceptable methods for handling incomplete data, so that readers will know what approaches to avoid; although analysis of complete cases is sometimes an acceptable solution, we argue that pairwise deletion and mean substitution should be avoided. With respect to newer, acceptable methods, we give a general overview, including a brief discussion of the full information maximum likelihood structural equation modeling procedures (such as Amos, Mx, LISREL 8.5, and Mplus), but focus primarily on multiple imputation as a general solution. We give specific guidelines for making use of state‐of‐the‐art multiple imputation software and step‐by‐step instructions for using multiple imputation with Schafer's (1997) NORM program. Empirical examples of exploratory and data quality analyses and a substantive illustration involving multiple linear regression demonstrate the use of multiple imputation in practice. The chapter concludes with a discussion of some practical issues that often arise in connection with the analysis of incomplete data.

This study focused on the strategies adolescents endorsed for situations in which friends were experimenting with alcohol, tobacco, and other drugs. Four hypothetical vignettes (concerning a friend smoking, using drugs, getting drunk at a party, or deciding whether to attend a party with alcohol and drugs) were presented to 2697 5th-12th graders. Whereas younger students were more likely to choose proactive strategies (talking to the friend or an adult or ending the friendship), older students were more inclined to say they would ignore a friend's smoking and drug use although they would take the car keys away from a friend drinking alcohol. Among those 13 years old and older, the more dangerous the substance, the more inclined the youth were to intervene. Females were more inclined than males to talk to friends about smoking, drinking, and drugs and less inclined to ignore the behaviors or stop being a friend.