gcse to alevel physics - key terms

valid measurement

when it measures what its supposed to be measuring

accurate result

when its close to the true value

precise results

when repeat measurements are consistent/agree closely with eachother

repeatability

how precise repeated measurements are when theyre taken by the same person, equipment, and conditions

uncertainty of a measurement

interval within which the true value is expected to lie

measurement error

difference between measured and true value

random error

caused by results unpredictably varying around the true value

systematic error

consistent difference between measured and true value

zero error

measuring instrument gives a false reading when it should be zero

independent variable

changed by the investigator

dependent variable

measured every time independent is changed

fair test

only the independent variable affects the dependent variable

control variables

kept constant to avoid affecting dependent variable