• Welche Arten von Ansaetzen haben wir in Kostenschaetzung?
  • Top-Down: Schaetzung anhand von Anforderungen. “Wir muessen Anforderungen X,Y,Z erfuellen, was muss dafuer getan werden?”
  • Bottom-Up: Entwicker schaetzen Anhand von Komponenten
• Basic Formula fuer Maintenance Cost Estimation
  • Effort = Size / Productivity (wie viel Mannmonate wird man benoetigen)
  • Cost = Effort * MonthlyRate (Anzahl PM * PM Preis)

Top-Down

• Welche Top-Down Ansaetze gibt es?
  • Algorithmic cost estimation: LOC-based, Function Point-based, COCOMO 2
  • Expert Judgement: estimation of several experts until consensus is reached
  • Estimation by analogy (Vergleicht mit fueheren vergleichbaren Projeten)
• LOC-Based Estimation erklaeren
  • Decompose project into a set of standard components specific to an application area
  • Use historical data to estimate the size (LOC) of each standard component. Make optimistic, most likely and pessimistic estimations.
  • Final size estimation is a weighted sum over these three estimation.
• Function Point-based Estimation erklaeren
  • Function point (FP) = unique and atomic piece of functionality as perceived by the user
  • Similar to LOC-based, but FP instead of LOC
• COCOMO erklaeren
  • COCOMO: Constructive Cost Model
  • COCOMO 1 assumes waterfall model
  • COCOMO 2 takes agile techniques into accoutn
  • Three estimates, after Early Prototype, Early Design, Post-Architecture
  • Was einberechnet wird: LOC, Entwicklererfahrung, Risks, Reuse degree, Platform difficulty, Tools, Unstanding of source code
• Nachteile von Top-Down Ansaetzen
  • Unsicheheit am Anfang ist sehr hoch, Anforderungen koennen im Laufe des Projekts geandert werden.
• What is Early Prototype in COCOMO?
  • "Early Prototype" mode is used when the software development team has created a preliminary version of the software that can demonstrate some of the key features and functionalities of the final product. This mode is often used during the early stages of development when the requirements are not fully known, and the goal is to create a basic version of the software to test the feasibility of the project.
  • Prototype to teast feasibility
• What is Early Design in COCOMO?
  • "Early Design" mode is used when the software development team has a detailed understanding of the project requirements and has created a preliminary design for the software. This mode is used when the development team has a clear idea of the features and functionalities of the software, and the goal is to refine the design and estimate the effort required to build the final product.
  • First design is created, that will be refined
• What is Post Architecture in COCOMO?
  • This mode is used when the software development team has completed the design of the software architecture and has received approval for it from the relevant stakeholders. At this stage, the development team has a clear understanding of the structure of the software and the interactions between its various components.

Bottom-Up

• Welche Bottom-Up Ansaetze gibt es?
  • Each developer fills out a Software Component Estimation Form for each part of the system
• Nachteile von Bottom-Up Ansaetzen
  • Integration von Komponenten wird oft unterschetzt oder komplett vergessen
  • Integration effort can be estimated by number of test cases of integration test

Cone of Uncertainty

• Cone of Uncertainty zeichen und erklaeren

  • Kosten-Zeit Diagram
  • Kosten: 1/4x bis 4x
  • Uncertainty in estimations is closely related with the uncertainty in how decisions will be made
  • Nach Projektphasen wird Uncertainty kleiner
  • Am Ende kenn man, wie viel Geld man gebraucht hat

  

• Wie kann man die Uncertainty verkeinern?

  • Entscheidungen Treffen