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4.36 Method Category "Estimation Models" (EMOD)  

  4.36 Methodenkategorie "Schätzmodelle" (SMOD)

Contents  
  • 1 Identification/Definition of the Method
  • 2 Brief Characteristic of the Method
  • 3 Limits of the Methods Application
  • 4 Specification of the Methods Allocation
  • 5 Interfaces
  • 6 Further Literature
  • 7 Functional Tool Requirements

    • 1 Identification/Definition of the Method

    "Estimation Models" (EMOD) is a category of methods; the individual applicable methods (estimation procedures) are described in more detail in EMOD - Estimation Models (in Annex 1) by listing the selection criteria. A special method is only defined within the scope of the operationalization.

    2 Brief Characteristic of the Method

    Objective and Purpose

    EMOD is the basis for an effort estimation that is as objective and as realistic as possible. The applied method is to guarantee an comprehensible, reliable, and precise estimation of effort.

    Operational Sequence

    The procedures used for the estimation methods of the category EMOD can be generalized as follows:

    Since the project is structured into clearly defined subtasks, it is necessary to specify and evaluate the criteria that are having an impact on the effort estimation. This refers to characteristics of the product (system), the project, the personnel, and the technology.

    The project size also specified by means of estimation is used as a basis for the effort estimation. It is measured in LOC (lines of code), documentation pages, number of functions and data structures, etc. By means of a computational rule and by applying criteria having an impact on the project the estimated project size will be converted into effort units (usually man months, but also man days, man weeks, or man years). Both the total effort (macro estimation) and the effort for the individual subtasks (micro estimation), i. e. for the submodels SD, QA, CM and PM as well as for the corresponding main tasks and subtasks have to be specified.

    By taking into consideration the special situation of the project and the company, the required time and cost units have to be deviated from the effort estimation.

    In order to get most realistic estimated values it is necessary to integrate the actual values for effort, time, and cost according to the progress of the project, and to set up a database containing the empirical information about the already completed projects and about the current project. Apart from the estimated values and the actual values, this experience database must store the marginal conditions and influencing criteria with regard to the estimation or to the possible deviations in a form that can be utilized.

    3 Limits of the Methods Application

    Basically, a large number of methods exists to support the effort estimation. The selection of one of these methods and the corresponding standardization is connected with various problems, though:

    4 Specification of the Methods Allocation

    No. Activity Description
    4.1 PM1.5 - Generation of Preliminary Plan Method EMOD is applied in PM1.5 to realize a preliminary effort estimation.

    With regard to planning activity PM1.5, the application of EMOD covers subproduct Project Plan.Efforts (Planned and Actual) for SD/QA/CM/PM Activities which, however, is completed by a comparison of planned and actual values during the course of the project.

    4.1 PM4 - Detailed Planning In case a deviation from the preliminary planning or the detailed estimation must be expected which is based on the progress of the project, EMOD must be applied to realize the preliminary estimation again (compare 4.1).

    In the case, the coverage of the corresponding product is the same as listed in 4.1.

    When applying method EMOD within the scope of the detailed planning, the estimated values for the main activities generated in the preliminary planning must be further subdivided. The effort for each individual subactivity of the project, i. e. for each instantiated subactivity in the work breakdown structure, has to be calculated with the help of the estimation model and must be entered into the subproduct in subproduct Project Plan.Efforts (Planned and Actual) for SD/QA/CM/PM Activities. The coverage of the subproduct Project Plan.Planned Values can only be achieved by applying the EMOD together with NPT - Network Planning Technique or BAR - Bar Plan; NPT or respectively BAR will then utilize the results of EMOD and convert them into a graphical representation.

    5 Interfaces

    - not applicable -

    6 Further Literature

    /Boehm, 1981/ Software Engineering Economics
    /Busch, 1972/ Delphi-Methode
    /Noth, 1984/ Aufwandschätzung von DV-Projekten Darstellung und Praxisvergleich der wichtigsten Verfahren
    /Putnam, 1980/ Software Cost Estimating and Life-Cycle-Control (Tutorial)
    /Reifer, 1989/ Economics of Ada: Estimation and Control
    /Tumm, 1972/ Die neuen Methoden der Entscheidungsfindung

    7 Functional Tool Requirements

    SPM05 - Supporting Cost Estimation

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