(from the chapter) The enormous growth in Internet-based research over the past decade has brought with it numerous questions about the most effective way to administer surveys and experiments via the Web. Some research has already been done examining seemingly minor but methodologically substantial issues, such as the relative effectiveness of different presentation formats. Formats can have an effect on sampling: Buchanan and Reips (2001), for instance, found personality differences between Macintosh and PC users, and educational differences between those who had JavaScript turned on in their Web browsers and those who did not. One of the few disadvantages of Internet-based research is the difficulty of ensuring understanding of the instructions and materials with remote participants (Reips, 2002c), so every effort should be taken to ensure that Internet-based studies are designed most appropriately to fulfill this prerequisite. The present chapter summarizes what can be done and covers basic information that helps researchers (1) become sensitive to design and formatting issues and identify how they may play a role in their Internet-based research and (2) find out how to best create and run their own Web studies in a way that design and formatting do not interfere with the research but rather support its cause. This chapter will thus be useful to behavioral scientists who are considering Internet-based data collection as part of their research strategy or as a topic of their teaching. It will also be useful to those who are considering setting up traditional laboratory studies with Internet technologies or are creating Web pages to interact with users, clients, or students in any other ways. Researchers who read this chapter will be able to identify how and why a certain way of designing a Web study may be a useful method for their research and what to look out for when choosing a different format. It will also help in analyzing work by others, as a reviewer of a paper or grant proposal, for example, or as a teacher, and will help in pinpointing likely problems with the design. (PsycINFO Database Record (c) 2010 APA, all rights reserved)