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Abstract: Scientific LogAnalyzer is a platform-independent interactive Web service for the analysis of log files. Scientific LogAnalyzer offers several features not available in other log file analysis tools—for example, organizational criteria and computational algorithms suited to aid behavioral and social scientists. Scientific LogAnalyzer is highly flexible on the input side (unlimited types of log file formats), while strictly keeping a scientific output format. Features include (1) free definition of log file format, (2) searching and marking dependent on any combination of strings (necessary for identifying conditions in experiment data), (3) computation of response times, (4) detection of multiple sessions, (5) speedy analysis of large log files, (6) output in HTML and/or tab-delimited form, suitable for import into statistics software, and (7) a module for analyzing and visualizing drop-out. Several methodological features specifically needed in the analysis of data collected in Internet-based experiments have been implemented in the Web-based tool and are described in this article. A regression analysis with data from 44 log file analyses shows that the size of the log file and the domain name lookup are the two main factors determining the duration of an analysis. It is less than a minute for a standard experimental study with a 2 × 2 design, a dozen Web pages, and 48 participants (ca. 800 lines, including data from drop-outs). The current version of Scientific LogAnalyzer is freely available for small log files. Its Web address ishttp://genpsylab-logcrunsh.unizh.ch/.

Abstract: WEXTOR is a Javascript-based experiment generator and teaching tool on the World-Wide Web that can be used to design laboratory and Web experiments in a guided step-by-step process. It dynamically creates the customized Web pages and Javascripts needed for the experimental procedure and provides experimenters with a print-ready visual display of their experimental design. WEXTOR flexibly supportscomplete and incomplete factorial designs withbetween-subjects, within-subjects, andquasi-experimental factors, as well as mixed designs. The software implements client-side response time measurement and contains a content wizard for creating interactive materials, as well as dependent measures (graphical scales, multiple-choice items, etc.), on the experiment pages. However, it does not aim to replace a full-fledged HTML editor. Several methodological features specifically needed in Web experimental design have been implemented in the Web-based tool and are described in this paper. WEXTOR is platform independent. The created Web pages can be uploaded to any type of Web server in which data may be recorded in logfiles or via a database. The current version of WEXTOR is freely available for educational and noncommercial purposes. Its Web address is http://www.genpsylab.unizh.ch/wextor/index.html.

Abstract: In fall 1995, the worldwide-accessible Web Experimental Psychology Lab (http://www.genpsylab. unizh.ch) opened its doors to Web surfers and Web experimenters. It offers a frequently visited place at which to conduct true experiments over the Internet. Data from 5 years of laboratory running time are presented, along with recommendations for setting up and maintaining a virtual laboratory, including sections on the history of the Web laboratory and of Web experimenting, the laboratory’s structure and design, visitor demographics, the Kids’ Experimental Psychology Lab, access statistics, administration, software and hardware, marketing, other Web laboratories, data security, and data quality. It is concluded that experimental data collection via the Internet has proven to be an enrichment to science. Consequently, the Web Experimental Psychology Lab will continue and extend its services to the scientific community.