Reliability,+Accuracy+and+Precision

__Reliability__

Repeats = Reliability

Definition: How much you can count on your results, how reliable are they? Reliable results are indicated by the fact that when you repeat a test there is only a little bit of variation (difference) between your measurements.

Examples:
 * I will repeat my test 5 times instead of 3 to make it more reliable.

__Accuracy__ Definition: How close the real answer are your measurements. To make a measurement accurate you need to both use the correct piece of equipment and do so in the proper way.

Examples:
 * I will measurement pH using a pH meter instead of universal indicator as it is more accurate.
 * I will measure the volume by holding the measuring cylinder at eye level as it is more accurate.

__Precision__ Definition: If you repeat your test are you likely to get the same, or almost the same result? If so it is a precise measure.

N.B. This is very similar to reliability, but reliability includes natural variation whereas precision focus just on the method and equipment used for measuring.