End-user programmers develop more software than any other group of programmers, using software authoring devices such as multimedia simulation builders, e-mail filtering editors, by-demonstration macro builders, and spreadsheet environments. Despite this, there has been only a little research on finding ways to help these programmers with the dependability of the software they create. We have been working to address this problem in several ways, one of which includes supporting end-user debugging activities through interactive fault localization techniques. This article investigates fault localization techniques in the spreadsheet domain, the most common type of end-user programming environment. We investigate a technique previously described in the research literature, and two new techniques. We present the results of an empirical study to examine the impact of two individual factors on the effectiveness of fault localization techniques. Our results reveal several insights into the contributions such techniques can make to the end-user debugging process, and highlight key issues of interest to researchers and practitioners who may design and evaluate future fault localization techniques.