Errors In Chemical Analysis

Measurand

quantity intended to measured (including type of measurement property and description of the state of substance)

Measurement Accuracy

how close the measured quantity value is to the true quantity value of the measurand

Measurement Trueness

the closeness of agreement between the average of an infinite number replicate measured quantity values and a reference quantity value (how close the average of many repeated measurements is to the true or reference value)

Measurement Precision

closeness of agreement between indications or measured quantity values obtained by replicate measurements on the same or similar objects under specified conditions (how close repeated measurements are to each other)

Measurement Error

measured value - reference value

Systematic Error

component of measurement error that in replicate measurements remains constant or varies in а predictable manner

= measurement error - random measurement error

Measurement Bias

estimate of a systematic measurement error (a repeatable, non-random deviation that pushes results away from the true value in a single specific direction)

Random Error

component of measurement error that in replicate measurements varies in an unpredictable manner

Parallax Error

 error in the placement of viewing (a type of systematic error) 

Round Robin Experiment

different people in several labs analyze identical samples by the same or different methods. disagreement beyond the estimated random error is systematic error

Measurement Uncertainty

describes how much the measured value may vary or how spread out the possible values of a measurand are (how much variation is associated with a measurement)