It's important to remember that a lot of products marketed today are sold in a multitude of markets globally. Where different conditions need to be considered in the functional testing process.
A product in one market may need to withstand high temperatures and humidity. Whilst in another market, the temperatures to withstand are near freezing or below, making the testing in extreme conditions a must in any testing program.
It is essential to test products for every market in which the product will be used
These extremes would be classed as bad data but more importantly what happens when ugly data is introduced. In this example, ugly data would include high temperatures and rapid changes to low temperatures and vice versa over a prolonged period.
This could cause the functions/components to fail. As an example the lights on the vehicle could be tested in extremes of temperature to see whether they still managed to function.
One particular car caused it's manufacturer some embarrassment, when parked cars simply started rolling down hill on their own accord when the temperatures were very low.
The cars caused an immense amount of damage, from rolling into houses, other vehicles and of course damage to themselves from the impact suffered.
Whilst the hand braking system had been tested, the manufacturer had failed to consider abnormal conditions where the outside temperature was lower than tested.
When the handbrake was applied, the braking mechanism would brake by using the front brake discs. Which when the car had been running would have become hotter and as a consequence would have expanded slightly.
When the car was parked and the handbrake was engaged the brake pads would engage the front discs. This would stop the car from rolling.
However as the discs cooled down, they began to contract and in extreme colder temperatures the level to which they contracted meant that the grip from the brake pads to the discs, lessened causing the cars to roll.
The extreme coldness of the temperature would have been classed as ugly data. Data which the discs and brake pads were not designed to handle.
As a consequence the manufacturer had to eventually compensate for the damage caused by the cars rolling out of control and rectify the hand brake system design.
When a new design of commercial plane is released there are certain tests that a plane must undergo to ensure that it meets the air safety requirements set out by the Federal Aviation Administration (FAA).
Whilst the standard, good data and it's bad data counterparts are used to determine the satisfactory level of functionality of the components within the airplane, there is one test where ugly data is introduced that really catches the eye.
This test is called the tail strike test, where the plane takes off at a sharper than normal angle causing the rear of the plane to strike the ground. This causes damage to the rear of the plane and the tail.
The testers then measure the functionality of the plane, as with the good and bad data tests whilst the plane is in the air and then when it lands. If a plane does not perform as expected, that is, it can't fly or land with the moderate tail strike damage, then the plane model will not receive it's airworthiness certificate.
This test is not done on all planes, as this would simply not be practical. This is due to the fact that the planes would be damaged, therefore this test is only done to the initial plane or planes released.
It can be difficult to determine how much testing is required. The next section focuses on determining the level of testing required.Summary
The abnormal conditions include applying bad and ugly data.
Testing under abnormal conditions includes using a product under conditions which it was not designed for.
Testing under abnormal conditions is necessary to ensure that a product can meet different global demands.