Precision, accuracy, reliability, validity

accuracy

Accuracy is how close a measured value is to the actual (true) value. aCcurate is Correct (a bullseye).

precision

Precise means things have been measured as accurately as possible, giving better quality data. The choice of equipment will impact on precision. e.g. using a light gate to measure timings is more precise that a stop clock.

quality

Quality of data can be linked to precision but also can be improved by taking extra readings e.g. to extend the range or fill in gaps. Also, taking readings with a more even spread over the range can help improve quality

reliability

The repeating of an experiment that produces comparable results. Reliability refers to the ability to perform the same experiment and get the same results. Discard or re-test anomalous results

validity

Valid data comes from a fair test, e.g. keeping control variables the same. .