How to Calculate Experimental Errors
Most recent answer: 03/22/2014
- Miriam (age 19)
Damascus, Syria
That's a very nice question. Everything you say through your "final result" makes sense. People usually don't use the average absolute value of the error but rather the square root of the average of the squared error, called the standard deviation, but for many purposes your choice is just fine.
The use of half the smallest increment is a decent approximation in certain cases, if some conditions hold:
1. You can't read the scale to better than the smallest marked increment. E.g. maybe it's a digital readout. Otherwise the error could be smaller than half the increment.
2. There are no other sources of noise. Otherwise the error could be much larger than half the increment.
The second condition usually doesn't apply. In your case, for example, the fluctuations between measurements were obviously larger than that.
So far as I can tell, you were right. The teacher was just telling you to follow orders and not think about what anything meant. We see that sort of teaching all too often at all levels.
Mike W.
(published on 03/22/2014)