Horizontal dispersion of software functional size with IFPUG and COSMIC units

Software development companies today are widely using software functional size measurement (FSM) as the main variable to assess the effort and time needed to perform a new software project. In the recent years, this has led to a grown interest in improving the way the measures are taken.In such sense, one of the main aspects that could have impact on measurements and that has not been enough studied is the error introduced by the measurer of the software application, through the subjectivity that can be introduced in the interpretation of the unit application rules. Such error could be evident in a measurement dispersion, defined in this paper in two possible ways: (a) Horizontal Dispersion, where the error could be introduced by the fact that two or more different people counted the same application at the same moment in the project development; and (b) Vertical Dispersion, where the error could be introduced by same measurer that count the same application at different times during the development.Since its definition by Albrecht in 1979 and its subsequent change of name in 1986, IFPUG function points have been the functional software measurement unit mostly applied, despite the definition and standardization of other variants such as NESMA, Mk-II, or more recently FiSMA. However in recent years a new method has been introduced called COSMIC that has been defined as a 2nd-generation FSM method, attracting the interest of the international software measurement community.The aim of this research is to draw some preliminary conclusions from statistical analysis of the software functional size data in which the horizontal dispersion degree could have been introduced in measurements taken into account IFPUG and COSMIC methods.