Scientific Method

• Accuracy


  the accuracy of a measurement relates to how close it is to the 'true' value of the quantity being measured

  so like, how close it is to the bullseye of a target
• Precision


  refers to how closely a set of measurement values agree with each other. gives no indication of how correct the values are

  eg. you shoot 10 arrows and they land at the exact same place (around at least). does not have to be near the bullseye, but it is still precise
• Reliability


  similar to precision, but incorporates the idea of significance in results - the confidence it is not due to chance
• Validity


  a measurement is valid if it measures what it is supposed to be measuring. an experiment is valid if it investigates what it sets out/claims to investiate