sometimes compound and at other times cancel

[Soo-Jin Heo]

Hi,

Can anyone help me with understanding the meaning of these two verbs below?
I looked them up in a dictionary but couldn't guess. The context is that they calcuate some figures
and talk about accuracy.
Thank you!

*Experience shows that inaccuracies can sometimes compound and at other times cancel each other.

 

[Barque]

In this context,

compound (WR dictionary): to increase or add to, esp. so as to worsen: When he started arguing with the police officer it only compounded his problems.
cancel (WR dictionary): to balance; make up for: His sincere apology canceled his sarcastic remark.

Inaccuracies can sometimes make the effect of other inaccuracies worse, and can sometimes compensate for other inaccuracies.

 

[dojibear]

If a calculation is wrong by 5%, and a later calculation is also wrong by 5%, the final value may be 10% wrong, or 0% wrong. It depends on whether the two errors were in the same direction or the opposite direction.

Two opposite mistakes "cancel each other" if the result is 0% wrong. They "compound each other" if it is 10%.

In general "compound" is not precise. See examples in #2. "Cancel" is often precise, meaning one thing removes the result of another.