My question was not specific enough last time, and so this is second question about this topic. 
I'm running some experiments and I need to precisely measure participants' response time to questions in millisecond unit. 
I know how to do this with the time module, but I was wondering if this is reliable enough or I should be careful using it. I was wondering if there are possibilities of some other random CPU load will interfere with the measuring of time.
So my question is, will the response time measure with time module be very accurate or there will be some noise associate with it?
Thank you,
Joon
CPU load will affect timing. If your application is startved of a slice of CPU time, then timing would get affected. You can not help that much. You can be as precise and no more. Ensure that your program gets a health slice of cpu time and the result will be accurate. In most cases, the results should be accurate to milliseconds.
Is python time module reliable enough to use to measure response time?