Sensitivity and Uncertainty Analysis

Question 1

Absolute error (of a measuring instrument)

Answer 1

The difference between the value of the measured quantity obtained by using a measuring instrument and the true (but unknown) value of the measured quantity.

Question 2

Absolutely constant elementary error

Answer 2

An elementary error that retains the same value in repeated measurements performed under the same conditions. The value of an absolutely constant error is unknown but its limits can be estimated.

Question 3

Accuracy of measurement

Answer 3

A qualitative expression of the closeness of the result of a measurement to the true value of the measured quantity.

Question 4

Accuracy of a measuring instrument

Answer 4

The ability of a measuring instrument to produce measurements whose results are close to the true value of the measured quantity.

Question 5

Combined measurement

Answer 5

Measurement of several quantities of the same kind, using results from (and/or combinations of) direct measurements.

Question 6

Conditionally constant elementary error (of a measurement)

Answer 6

An elementary error, having definite limits, which varies in repeated measurements performed under the same conditions or with different measuring instruments of the same type. These limits can be calculated or estimated.

Question 7

Dead band

Answer 7

Maximum interval through which a stimulus may be changed in either direction without producing a change in the response of a measuring instrument.

Question 8

Drift

Answer 8

A slow variation in time of the output of a measuring instrument, independently of the respective stimulus.

Question 9

Elementary error (of a measurement)

Answer 9

A component of error or uncertainty of a measure- ment associated with a single source of inaccuracy of the measurement.

Question 10

Error (of a measurement)

Answer 10

The deviation of the result of a measurement from the true value of the measured quantity; the error is expressed in absolute or relative form.

Question 11

Inaccuracy (of a measurement)

Answer 11

A qualitative characteristic of the deviation of a measure- ment result from the true value of the measured quantity. Quantitatively, inaccuracy can be characterized either as a measurement error or as a measurement uncertainty.

Question 12

Indirect measurement

Answer 12

A measurement in which the value of the measured quantity is cal- culated by using measurements of other quantities that are connected to the measured quantity by a known relation.

Question 13

Intrinsic error

Answer 13

The error of a measuring instrument, determined under reference condi- tions.

Question 14

Measurement

Answer 14

The set of experimental operations that are performed using technical products (measuring instruments) for the purpose of finding the value of a physical quantity.

Question 15

Measuring instrument

Answer 15

A technical product with standardized metrological characteristics.

Question 16

Measuring standard

Answer 16

A measuring instrument intended to materialize and/or conserve a unit of a physical quantity in order to transmit its value to other measuring instruments.

Question 17

Metrology

Answer 17

Science of measurement: an applied science that includes knowledge of mea- surements of physical quantities.

Question 18

Normal operating conditions

Answer 18

Conditions within which a measuring instrument is designed to operate so that its metrological characteristics lie within specified limits.

Question 19

Primary standard

Answer 19

A measuring standard that has the highest accuracy (in a country).

Question 20

Random error (of a measurement)

Answer 20

A component of the inaccuracy of a measurement that varies in an unpredictable way in the course of repeated measurements of the same measured quantity under the same conditions.

Question 21

Relative error

Answer 21

Absolute error divided by the true value of the measured quantity. In practice, the true (but unknown) value is replaced by the measurement result.

Question 22

Repeatability of a measurement:

Answer 22

The closeness of agreement among several consecutive mea- surements of the same quantity, performed under the same operating conditions with the same measuring instruments, over a short period of time.

Question 23

Reproducibility of a measurement

Answer 23

The closeness of agreement among repeated measure- ments for the same measured quantities performed in different locations, under different operating conditions, or over a long period of time.

Question 24

Resolution

Answer 24

The smallest, still distinguishable interval between two adjacent values of the output signal of a measuring instrument.

Question 25

Result of measurement

Answer 25

The value obtained by measurement of a quantity. The measurement result is expressed as a product of a numerical value and a proper unit.

Question 26

Sensitivity of a measuring instrument

Answer 26

The change in the response of a measuring instrument divided by the corresponding change in the stimulus.

Question 27

Systematic error (of measurement)

Answer 27

A component of the inaccuracy of measurement that remains constant or varies in a predictable way in the course of repeated measurements of the same measured quantity.

Question 28

True value

Answer 28

The value of a measured quantity that (if it were known) would ideally reflect, qualitatively and quantitatively, the respective property of the quantity of interest.

Question 29

Uncertainty of measurement

Answer 29

An interval within which the true value of a measured quantity would lie with a given probability. Uncertainty is defined with its limits and corresponding confidence probability, and can be expressed in absolute or relative form.