ISO 11843-5:2008 検出機能—パート5：線形および非線形キャリブレーションの場合の方法論 | ページ 6

3.1

critical value of the net state variable

x_c

value of the net state variable, X , the exceeding of which leads, for a given error probability, α, to the decision that the observed system is not in its basic state

[SOURCE:ISO 11843-1:1997, definition 10]

3.2

minimum detectable value of the net state variable

x_d

value of the net state variable in the actual state that will lead, with probability 1 − β, to the conclusion that the system is not in the basic state

Note 1 to entry: Adapted from ISO 11843-1:1997, definition 11 and ISO 11843-1:1997/Cor.1:2003.

3.3

precision

standard deviation (SD) of the observed response variable or SD of the net state variable when estimated by the calibration function

Note 1 to entry: Coefficient of variation (CV) may be used as precision instead of SD where appropriate.

Note 2 to entry: In this part of ISO 11843, precision is defined under repeatability conditions (ISO 3534-2).

Note 3 to entry: The terms, precision and precision profile, are used in this part of ISO 11843, rather than imprecision and imprecision profile, because of a tradition to use the former terms in a number of situations.

Figure 1—Distributions of the estimated net state variable in the basic state, X = 0, (left) and in the state of x_d (right)

Key

xc	critical value of the net state variable
xd	minimum detectable value of the net state variable
X	net state variable
α	probability of an error of the first kind at X = 0
β	probability of an error of the second kind at X = xd

^a Probability density.

NOTE Figure 1 in ISO 11843-1:1997 illustrates the distributions of response variables and the non-linear calibration line. Figure 1 of this part of ISO 11843 includes the distributions of net state variables which are transformed through the slope of the calibration line from the distributions of the response variable shown in ISO 11843-1.

3.4

precision profile

mathematical description of the standard deviation or coefficient of variation of the response variable or net state variable as a function of the net state variable

3.5

response variable

Y

variable representing the outcome of an experiment

[SOURCE:ISO 3534-3:1999, definition 1.2]

Note 1 to entry: For the purposes of ISO 11843, this general definition is understood in the following specialized form: directly observable surrogate for the state variable, Z .

Note 2 to entry: The response variable, Y , is a random variable in any stage of analysis and if transformed by the calibration function, its precision profile is expressed as the standard deviation and coefficient of variation, σ_X ( X ) and ρ_X ( X ), respectively, of the net state variable.

3.6

precision profile of response variable

continuous plot in this part of ISO 11843 on the basis of the uncertainty of the response variable which comes from the random properties of analytical steps such as pipetting and instrumental baseline noise, and not from the systematic error often known as the knowledge of instrumental imperfections

3.7

net state variable

X

difference between the state variable, Z , and its value in the basic state, z₀

[SOURCE:ISO 11843-1:1997, definition 4]

Note 1 to entry: The net state variable, X , is a deterministic variable in the stage where a calibration line is prepared, and the precision profile, expressed as σ_X ( X ) and ρ_X ( X ), originates from the randomness of the response variable.