1. Why hitting your target is not always good.
Precision vs. Accuracy
Why hitting your target is not always good.

2. Precision
Precision refers to how well an instrument is capable of measuring
For example, how accurate would we be if we attempted to measure out .5mL in a large beaker?
We would have very little luck probably. We could only sure of our answer to + or – 5mL as stated on the beaker
Even if we do get lucky and get .5mL in the beaker this measurement is still not precise because of the choice of instrumentation

3. Accuracy
Accuracy refers to how close you actually came to the correct measurement
With accuracy it is not important how or why the measurement is correct, we do not care about precision
Example may be if a bullet is fired up into the air from a handgun, with dumb luck it comes down on a criminal committing a felony
Was the shot accurate? Yes
Was the shot precise? NO!!!

4. Precision and Accuracy
Ideally we would like for our results to be both precise and accurate though this is not often possible
However, the more precise the instrument the greater the chance that accuracy will follow