Practical Science Key Terms

Valid measurements

When a method accurately measures what is meant to be measured

Accurate Results

When results are close to true value

Precise Results

When results are close together

Repeatability

How accurately results can be produced again by the same person with the same equipment and conditions

Reproducibility

How accurately results can be produced again by a different person with different equipment and conditions

Uncertainty of a measurement

Interval in which the true value of a measurement is expected to be

Measurement error

Difference between measured value and true value

Random error

Error caused by results varying around true value in an unpredictable way

Systematic Error

Consistent difference between measured values and true values, usually caused by miscalibration of measuring equipment

Zero Error

Measuring equipment showing incorrect reading when true value should be 0

Fair test

A test in which only the independent variable is allowed to affect the results