![](bg6.png)
Finally, a “conventional reference scale/reference-value scale” represents particu-
lar quantities of a given kind, an ordered set of values, continuous or discrete, and is
defined by convention as a reference for arranging quantities of that kind in order of
magnitude. In COSMIC-FFP, this concept corresponds to the scale of a movement of
a data group (entry, exit, read, and write, abbreviated by convention as “E” for entry,
“X” for exit, “R” for read, and “W” for write). Each movement of a data group has a
size of 1 Cfsu in COSMIC-FFP. There is, of course, a standard definition of what is
recognized as a “data group” by COSMIC-FFP. In addition, it represents a discrete
set of values composed of E = X = R = W = 1.
In COSMIC-FFP, the “numerical value” of the software to be measured corre-
sponds to the addition (in the same software layer) of the individual values assigned
to each identified movement of a data group. This addition provides the “numerical
value” of the software to be measured. In short, “numerical value” and “conventional
reference scale” are explicitly defined in the COSMIC-FFP standard [10].
3.2 Measurement standards – Etalon
In measurement for the sciences and for engineering, it is taken for granted that
there should exist “measurement standards - etalons” for calibrating and verifying the
measuring instruments and to ensure the consistency of measurement results across
individuals, organizations, and nations. However, this metrology concept has not yet
been discussed in the software measurement literature, nor has it been the focus of
attention of practitioners. In software measurement, what could be close to this con-
cept, and its related sub-concepts in Table A.4, are the case studies documented for a
few of these software FSM methods.
4. Analysis of Measurement with COSMIC-FFP
In the VIM, the term “measurement” refers to the category of terms for the “set of
operations” required to obtain a measurement result (see also Fig. A.1), and this is
instantiated through the generic measurement process described in Fig. A.2.
This figure illustrates, with the use of a graphical representation of a process, dif-
ferent concepts related to the concept of “measurement”. It should be noted that, in
metrology, the “quantity to be measured” by means of a set of operations (and a
measuring instrument) is also called a “measurand”, that is, the input quantity that is
applied to a measuring instrument (Fig. A.2).
As described in Fig. A.2, a measurement procedure requires, as input, a meas-
urand, which corresponds in COSMIC-FFP to the FURs, and produces a measure-
ment result which represents a numerical value of functional size. An instantiation of
a measurement procedure for a specific measurement includes an operator to carry
out the measurement process (here, the measurer), the measurement method itself
(here, the standard method), and the influence quantities (here, conditions that could
influence/ bias measurement results). The operator corresponds to the user of the
method (the measurer). The COSMIC-FFP measurement method is explicit, and the
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