Types of Error

systematic error

errors which show a pattern or trend and can result from an instrument calibration error or from incorrect use or reading of the instruments

random error

resulting from inconsistency, error that has equal probability of being too high or too low.

personal error

result from limits of human senses or carelessness on the part of the experimenter

lag error

An error that results from not giving the measurement tool enough time to settle or reach equilibrium.

incomplete definition

The procedure for making the correct measurement is not clearly defined.

instrument resolution

The precision of the tool limits the ability to resolve small measurement differences.

calibration errors

The tool is not zeroed, causing all measurements to be incorrect.

physical variation

Measurements in different areas or ranges on the object being measured result in different measurements due to imperfections in the object.

parallax

The observer's eyes are not perfectly aligned with the measurement scale.

instrument drift

Electronic measurement tools have readings that drift over time.

environmental factors

Vibrations, drafts, changes in temperature can effect the measurement and must be controlled.

Precision

a measure of how close a series of measurements are to one another

Accuracy

A description of how close a measurement is to the true value of the quantity measured.

zero offset error

An error such that the zero-point is set at something other than zero.

Instrument drift

Most electronic instruments have readings that change slightly over time.