Following the news

During the CAST 2014 conference in New York I participated in a workshop by Laurent Bossavit and Michael Bolton called “Thinking critically about numbers – Defense against the dark arts”. This workshop addressed the usage of numbers, measurements and the ability to influence their perception by choosing a certain representation, telling only parts of the information or leaving out context. Inspired by this workshop I took a look at one of the Dutch sites addressing news about software testing www. testnieuws.nl.

On Testnieuws I found an article about software errors invalidating school exams “Eindexamen ongeldig door softwarefout“. The story describes that the school inspection declared 1372 school exams invalid due to software errors. Especially software errors in the VMBO (a dutch school type) Math exam. Being a tester I was curious if could find out what had happened. The article written by Marco van der Spek referenced a newspaper article in “De Limburger“. Both articles were exactly the same, so my first conclusion was that in this case it was more of posting an article than writing an article. Something which is in line with the general practice of the site as it is more a collector of news than an actual writer of news stories. (To my knowledge the site only manned by a a few part-timers.)

Since the newspapers only indirect reference was mentioning the school inspection my search now focussed on looking for the source document there. On their site I found the original press release. The press release added much more detail with regard to all the exams, both written and digital, and differentiated the 1372 number as follows:

  • 127 cases of technical problems (film not running, computer not working correctly)
  • 112 cases of non technical problems (running out of time, fire alarm, usage of wrong materials)

That brought the number of potential Math exam problems down to 1133. The press release also mentioned what the problem with the Math exam was. It was not that the digital exam had produced obvious software errors or that functionality had not been available. The exam had offered the usage of an build-in calculator that handled negative numbers differently than many of the calculators VMBO students had used during the school year. The school inspection had ruled that this had given the students a disadvantage and offered them the possibility to redo the exam if they so wished. 1133 students have made use of this offer.

So what does this mean?

First that the number 1372 school exams is arbitrary and for the most part based on the number of students that used the offer to redo the Math exam. This could also have been half or double the number. So mentioning that specific number does not add value to the story.

Secondly I see an oracle problem with regard to the conclusion that the software was in error. Based on the information I cannot tell if either the built-in calculator had actually produced wrong answers when using negative numbers or if the calculators used by the students did during the school year. (Assuming there is another oracle in form of a scientifically established rule to use negative numbers we could which of the two produced incorrect answers.)

Finally I see a case of shallow agreement on what a software error is. For some a software error is something that occurs when the software runs into a situation where it can not handle or produce the data and responds by showing an error message. Others see a software error when the software, in this case the calculator, is not functioning according to specifications. The built-in calculator may or may not have been functioning according to its specifications, we cannot tell based on the information.

I do like the school inspections response to the situation. They did not call any of it a software error but only mentioned that 1372 digital exams were declared invalid. They did however see the potential disadvantage for the VMBO students, which I think is an excellent oracle, and offered a solution for them to redo the exam.

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