Charles Lau, PhD, is a Survey Methodologist at RTI International, where he has led surveys in over 20 countries in Asia, Africa, and Latin America with over 200,000 respondents. He directs projects through the survey cycle, including study design, questionnaire development, sampling, interviewer training, data collection, analysis, and reporting. He has published research on cross-cultural issues in survey design, interviewer and mode effects, and sampling approaches in developing countries.