Volume 3, Issue 4, July 2018, Page: 77-86
Statistical Considerations on Software-Safety Estimation in Licensing
Wolfgang Ehrenberger, Department of Applied Informatics, University of Applied Science, Fulda, Germany
Received: May 15, 2018;       Accepted: Jun. 22, 2018;       Published: Jul. 25, 2018
DOI: 10.11648/j.mcs.20180304.11      View  644      Downloads  44
During the discussions in preparation of the new versions of the International Electrotechnical Commission (IEC) standards IEC 61508-3 and IEC 61508-7, controversies regarding the proper roles of statistical validation or verification of safety-related software have emerged. These controversies regard changing demand profiles and continuous operation versus on-demand operation. This contribution derives a formula for calculating the failure probability per demand of software that has been tested under a demand profile that is different from the profile of its intended use. It also explains how failure rates can be expressed in terms of failure probabilities per demand, if the operational conditions are known. It further describes how software that is alternately operated continuously and on demand can be characterized in statistical terms and how the two operation modes can be recognized during a statistical evaluation. The notion of “mission” is suggested for sequences of demands or mixtures of demand-driven and continuous operation of software. In order to allow statistical calculations many requirements have to be met strictly. They are listed in the appendix. This article can hopefully facilitate licensing of software in many cases. Remarks are invited.
Software Safety, Statistical Testing, Operational Experience, One-Sided Confidence Interval, Changing Demand Profile, On-Demand or Continuously Working, Missions
To cite this article
Wolfgang Ehrenberger, Statistical Considerations on Software-Safety Estimation in Licensing, Mathematics and Computer Science. Vol. 3, No. 4, 2018, pp. 77-86. doi: 10.11648/j.mcs.20180304.11
Copyright © 2018 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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