Burnett, Margaret M.

Fisher II, Marc

Rothermel, Gregg

Dagstuhl Research Online Publication Server

A Methodology to Improve Dependability in SpreadsheetsMargaret BurnettOregon State Universityburnett@eecs.oregonstate.eduMarc Fisher II, Gregg RothermelUniversity of Nebraska - Lincoln{mfisher,grother}@cse.unl.edu1 IntroductionSpreadsheets are one of the most commonly used end-user programming environments. As such, there hasbeen significant effort on the part of researchers andpractitioners to develop methodologies and tools toimprove the dependability of spreadsheets.Our work has focused on the development of the“What You See Is What You Test” (WYSIWYT)family of techniques. WYSIWYT is designed to beseamlessly integrated into a spreadsheet environmentand the user’s development processes. It uses visualdevices that are integrated into the user’s spreadsheetto guide the process of finding and fixing problemswith the spreadsheet.There are three major components to the WYSI-WYT methodology: a testing and debuggingmethodology, an assertions mechanism, and the“Surprise-Explain-Reward” strategy.2 Testing and DebuggingMethodologyWYSIWYT provides a testing and debuggingmethodology [3]. As the user edits their spreadsheetthey are provided with visual devices indicating the“testedness” (coverage relative to an underlying data-flow adequacy criterion) of the cells and the spread-sheet and the ability to mark the values in cells ascorrect or incorrect. If the user marks a cell’s valueas correct, the testedness of the contributing cells isupdated as is the testedness of the spreadsheet. If,instead, the user marks a cell’s value as incorrect, ad-ditional information is displayed to the user about the“fault likelihood” of cells based on the number of cor-rect and incorrect values to which they contribute[4].Figure 1 shows our visual devices in the Excel spread-sheet language.In addition to tracking testedness and fault likeli-hood, WYSIWYT includes a “Help-Me-Test” featurethat generates new test cases to cover unexercisedportions of the spreadsheet [2] or replays test casesto re-validate changed portions of the spreadsheet.3 Assertions MechanismWYSIWYT also includes an assertions mechanismwhere users can supply a valid range of values fora cell [1]. These ranges are then propagated throughdependent cells using interval arithmetic techniques,and conflicts between user-supplied ranges, propa-gated ranges and cell values are displayed to the user.The assertions mechanism interacts with Help-Me-Test in two ways. User-supplied ranges on cells whoseformulas are simple data values are used to limit theinputs used when generating new test cases. Help-Me-Test then attempts to generate test cases thatviolate the ranges on formula cells as they indicatethat the user has an error either in a formula or arange.4 Surprise-Explain-RewardA key strategy in getting end users to effectivelyutilize the WYSIWYT methodology is Surprise-Explain-Reward [5]. Surprise-Explain-Reward relieson a user’s curiosity about features in the environ-ment. According to research about curiosity, if theuser is surprised by something, such as the check-boxes in the spreadsheet, the surprise can arouse theuser’s curiosity, potentially causing the user to seekan explanation.All features and feedback must therefore be able toexplain themselves. These explanations must do twothings: first, make the user aware of why the itemis worthy of further attention (i.e., make the rewardsclear), and second, help the user make an informedjudgment as to whether the reward is worthwhile.Users explore a feature by viewing its explanation, ondemand, via tool tips and other low-cost mechanisms.1Dagstuhl Seminar Proceedings 07081End-User Software Engineeringhttp://drops.dagstuhl.de/opus/volltexte/2007/1088Figure 1: WYSIWYT Devices in the Excel Spreadsheet EnvironmentThe reward in the explanation informs the userwhen weighing costs, benefits, and risks in decidinghow to complete a task. By providing users a projec-tion of future benefits, they can better assess if thecost of using the feature is worth their time. If allgoes well, if the user follows up as advised in the ex-planation, rewards will ensue, such as an increase intesting coverage or the discovery of an error.5 Future WorkOur most recent research continues to investigateSurprise-Explain-Reward, focusing primarily on theexplanations aspect. We are doing significant experi-mental prototyping and empirical work to understandwhat end-user programmers actually want to knowwhen debugging, how explanations provided by thesystem can help them, and how they might be ableto help each other. We are thus looking into strate-gies end-user debuggers follow, whether the systemhelps to support these strategies, and whether the ex-planations are helpful in improving their debuggingstrategies.We are also interested in aspects of the end-usersoftware engineering lifecycle beyond testing and de-bugging, and how to support them.References[1] M. Burnett, C. Cook, and G. Rothermel. End-user software engineering. Communications of theACM, 47(9):53–58, September 2004.[2] M. Fisher II, G. Rothermel, D. Brown, M. Cao,C. Cook, and M. Burnett. Integrating automatedtest generation into the wysiwyt spreadsheet test-ing methodology. ACM Transactions on Soft-ware Engineering and Maintenance, 15(2):150–194, April 2006.[3] G. Rothermel, M. Burnett, L. Li, C. DuPuis,and A. Sheretov. A methodology for testingspreadsheets. ACM Transactions on Software En-gineering and Maintenance, 27(1):110–147, Jan-uary 2001.[4] J. Ruthruff, S. Prabhakararao, J. Reichwein,C. Cook, E. Creswick, and M. Burnett. Interac-tive, visual fault localization support for end-userprogrammers. Journal of Visual Languages andComputing, 16(1-2):3–40, February/April 2005.[5] A. Wilson, M. Burnett, L. Beckwith, O. Granatir,L. Casburn, C. Cook, M. Durham, and G. Rother-mel. Harnessing curiosity to increase correctnessin end-user programming. In Proceedings of theACM SIGCHI Conference on Human Factors inComputing Systems, pages 305–312, April 2003.2

A Methodology to Improve Dependability in Spreadsheets

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A Methodology to Improve Dependability in Spreadsheets

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