The final form of input again associated with abnormal conditions is using ugly data. This is data that is out of the ordinary. Whilst the possibilities of the user of the product applying such data maybe remote, it's consequences need to be assessed and controlled.
It can never be taken for granted that ugly data will never be introduced to a product.
So there's three types of data: the Good, Bad and the Ugly.
Ugly data has the possibility to damage and even destroy a product. More importantly it could injure the person using the product.
Examples of ugly data used on the alarm clock could be,
holding a button down for a prolonged period of time,
pressing and holding all the buttons together at once,
switching the alarm clock on/off over and over again.
Who's to say that using ugly data with the alarm clock doesn't cause it to electrically short and even electrocute someone?
Testing with bad and ugly data is essential in ensuring that a product is safe to use.
A set of journalists based in Sweden were driving a newly released car in the north of Sweden. They decided to see how well the car would cope if an elk (moose) ran across its path and they had to swerve violently to avoid it.
Whilst not being a normal driving procedure, the violent swerving acted as a ugly data input. Where it was something that could happen even though the likelihood of it happening was remote.
They drove the vehicle at normal speed and then turned the steering wheel violently as if to avoid an elk running across their path. The vehicle rolled over onto its side.
The journalists were very surprised that the vehicle rolled over so easily. This was not at all what they expected and clearly demonstrated that the vehicle may not be completely safe to drive.
The vehicle manufacturer initially argued that swerving violently as in the case with the Swedish journalists, was not the normal driving behaviour, therefore their vehicle was safe to drive and didn't require any modifications.
The vehicle manufacturer quickly realised that this stance could seriously damage their reputation, which in turn could seriously affect the sales of their new vehicle. This left little option other than to admit there was a stability problem and make corrections to reduce the effect of the violent steering movements.
To further highlight the importance of using bad and ugly data, consider the previous section 'Testing under normal conditions', where the Ministry of Transport, MOT test was highlighted as a test under normal conditions.
If a vehicle passes all the MOT tests, does that mean that the vehicle is safe to drive?
The MOT test cannot guarantee the safety of the vehicle under test. Simply because the tests done only fulfil the minimum requirement needed to prove that the vehicle is road worthy, which doesn't imply that it is safe to use.
The Swedish journalists mentioned earlier tested a new vehicle which would have easily have passed the MOT test. However, it transpired that driving the vehicle under abnormal conditions caused it to roll over. Highlighting that this particular vehicle was not safe to drive, irrespective of whether the manoeuvre used was expected during normal day to day driving.
By introducing abnormal conditions which are conditions which would probably not occur regularly in the day to day running of the vehicle, the safety level of the vehicle can be more thoroughly tested.
So whilst in the MOT test the steering can be tested to see if the steering components are in good condition and whether the play between the steering is acceptable. It's only when the vehicle is driven and the steering tested under abnormal conditions, can a better understanding of the safety of the steering systems be developed.
Driving at speed and turning the steering wheel sharply, will provide a better indication of how safe the steering is to use. Turning the steering wheel from left to right and vice versa in quick succession, over several minutes will also provide a better insight into the safety of the steering in the vehicle. Compared to just physically checking the components or testing the steering by turning it from left to right and vice versa during the vehicle being stationary.
It may be that turning the steering wheel sharply to the left and right causes unacceptable vibrations to travel through the steering column. Or the steering column breaks causing the vehicle steering to fail completely.
If after all the tests under abnormal conditions have been applied and the vehicle is still working as expected. Then it can be said that the vehicle is safe to use.