What is a `sanity test'?


This isn't a special or secret test. All we do is stop, take a deep breath, and look at our answer.

Sure we always look at our answers| or do we? This time we mean stop and really look| does
our answer make sense?

Imagine you were calculating the number of people in a classroom. If the answer you got was
1 000 000 people you would know it was wrong| that's just an insane number of people to have
in a classroom.
That's all a sanity check is| is your answer insane or not? But what units were
we using?
We were using people as our unit. This helped us to make sense of the answer. If we
had used some other unit (or no unit) the number would have lacked meaning and a sanity test
would have been much harder (or even impossible).
It is useful to have an idea of some numbers before we start. For example, let's consider
masses. An average person has mass 70kg, while the heaviest person in medical history had a
mass of 635kg. If you ever have to calculate a person's mass and you get 7000kg, this should
fail your sanity check| your answer is insane and you must have made a mistake somewhere.


In the same way an answer of 0:00001kg should fail your sanity test.
The only problem with a sanity check is that you must know what typical values for things
are. In the example of people in a classroom you need to know that there are usually 20{50
people in a classroom. Only then do you know that your answer of 1 000 000 must be wrong.


source : fhsstphy

Now you know about Sanity test.