Daniel Kulesz

Daniel Kulesz, Stefan Wagner

Spreadsheets (sometimes also called Excel programs) are powerful tools which play a business-critical role in many organizations. However, due to faulty spreadsheets many bad decisions have been taken in recent years. Since then, a number of researchers have been studying spreadsheet errors. However, one issue that hinders discussion among researchers and professionals is the lack of a commonly accepted taxonomy. Albeit a number of taxonomies for spreadsheet errors have been proposed in previous work, a major issue is that they use the term error that itself is already ambiguous. Furthermore, to apply most existing taxonomies, detailed knowledge about the underlying process and knowledge about the "brain state" of the acting spreadsheet users is required. Due to these limitations, known error-like phenomena in freely available spreadsheet corpora cannot be classified with these taxonomies. We propose Asheetoxy, a simple and phenomenon-oriented taxonomy that avoids the problematic term error altogether. An initial study with 7 participants indicates that even non-spreadsheet researchers similarly classify real-world spreadsheet phenomena using Asheetoxy.

Verena Käfer, Daniel Kulesz, Stefan Wagner

The better developers can learn software tools, the faster they can start using them and the more efficiently they can later work with them. Tutorials are supposed to help here. While in the early days of computing, mostly text tutorials were available, nowadays software developers can choose among a huge number of tutorials for almost any popular software tool. However, only little research was conducted to understand how text tutorials differ from other tutorials, which tutorial types are preferred and, especially, which tutorial types yield the best learning experience in terms of efficiency and effectiveness, especially for programmers. To evaluate these questions, we converted an existing video tutorial for a novel software tool into a content-equivalent text tutorial. We then conducted an experiment in three groups where 42 undergraduate students from a software engineering course were commissioned to operate the software tool after using a tutorial: the first group was provided only with the video tutorial, the second group only with the text tutorial and the third group with both. In this context, the differences in terms of efficiency were almost negligible: We could observe that participants using only the text tutorial completed the tutorial faster than the participants with the video tutorial. However, the participants using only the video tutorial applied the learned content faster, achieving roughly the same bottom line performance. We also found that if both tutorial types are offered, participants prefer video tutorials for learning new content but text tutorials for looking up "missed" information. We mainly gathered our data through questionnaires and screen recordings and analyzed it with suitable statistical hypotheses tests. The data is available at [12]. Since producing tutorials requires effort, knowing with which type of tutorial learnability can be increased to which extent has an immense practical relevance. We conclude that in contexts similar to ours, while it would be ideal if software tool makers would offer both tutorial types, it seems more efficient to produce only text tutorials instead of a passive video tutorial - provided you manage to motivate your learners to use them.

Daniel Kulesz, Verena Käfer, Stefan Wagner

Spreadsheets are powerful tools which play a business-critical role in many organizations. However, many bad decisions taken due to faulty spreadsheets show that these tools need serious quality assurance. Furthermore, while collaboration on spreadsheets for maintenance tasks is common, there has been almost no support for ensuring that the spreadsheets remain correct during this process. We have developed an approach named Spreadsheet Guardian which separates the specification of spreadsheet test rules from their execution. By automatically executing user-defined test rules, our approach is able to detect semantic faults. It also protects all collaborating spreadsheet users from introducing faults during maintenance, even if only few end-users specify test rules. To evaluate Spreadsheet Guardian, we implemented a representative testing technique as an add-in for Microsoft Excel. We evaluated the testing technique in two empirical evaluations with 29 end-users and 42 computer science students. The results indicate that the technique is easy to learn and to apply. Furthermore, after finishing maintenance, participants with spreadsheets "protected" by the technique are more realistic about the correctness of their spreadsheets than participants who employ only "classic", non-interactive test rules based on static analysis techniques. Hence, we believe Spreadsheet Guardian can be of use for business-critical spreadsheets.

Daniel Kulesz, Fabian Toth, Fabian Beck

Existing approaches for detecting anomalies in spreadsheets can help to discover faults, but they are often applied too late in the spreadsheet lifecycle. By contrast, our approach detects anomalies immediately whenever users change their spreadsheets. This live inspection approach has been implemented as part of the Spreadsheet Inspection Framework, enabling the tool to visually report findings without disturbing the users' workflow. An advanced list representation allows users to keep track of the latest findings, prioritize open problems, and check progress on solving the issues. Results from a first user study indicate that users find the approach useful.

Daniel Kulesz, Jan-Peter Ostberg

Just like other software, spreadsheets can contain significant faults. Static analysis is an accepted and well-established technique in software engineering known for its capability to discover faults. In recent years, a growing number of tool vendors started offering tools that allow casual end-users to run various static analyses on spreadsheets as well. We supervised a study where three undergraduate software engineering students examined a selection of 14 spreadsheet auditing tools, trying to give a concrete recommendation for an industry partner. Reflecting on the study's results, we found that most of these tools do provide useful aids in finding problems in spreadsheets, but we have also spotted several areas where tools had significant issues. Some of these issues could be remedied if spreadsheet auditing tool vendors would pick up some ideas of static analysis tools for traditional software development and adopt some of their solution approaches.