Chapter 5 Flashcards
What influences project costs during cost estimation
The factors are:
- The scope of the project, the functionality of the system to be built.
- Technical constraints and non-functional requirements e.g includes
- system performance, response time
- architectural constraints
- Project management issues:
- team qualification, business and technical experience
- project organization
- tool support
- Miscellaneous e.g your contractor may be very formal and difficult to work with.
Name the two widely used estimation techniques
- Functional point analysis, and
- Delphi method
What is the idea behind functional point analysis?
The idea is to measure the business complexity of the system to be built. The system is measured based on its functionality as well as other influencing factors.
Note: Business complexity and other factors result in the overall effort.
Highlight the three steps in functional point analysis
Measure the business complexity => Calculate additional factors => Calculate overall effort
- To measure business complexity, the system requirements are split up into list of items that are measured separately, each item in the list is assigned a complexity weighting of either low, average or high. The weighting is converted into functional point count.
The sum of the function points of all items is called the Unadjusted Function Point Count (UFC). This count represents the business complexity of the system regardless of technological aspects.
- Calculate additional factors
The system technical and operational characteristics are calculated next. They are accumulated in the Value Adjustment Factor (VAF) - Calculate overall effort
The overall effort is calculated by multiplying the UFP and VAF which leads to the Final Function Point Count.
To get effort estimation the FPC has to be converted into persons-days.
Estimation models like Functional point analysis
Are very company- specific.
What is Use case point analysis?
It is a variation of Functional point analysis where business functionality is broken down into use cases instead of single functions.
Value Adjustment Factor formula
Formula according to IFPUG
VAF = (TDI * 0.01) + 0.65
TDI - Total Degree of Influence
What is the idea behind Delphi method for effort estimation?
The idea is to have experts estimate the efforts of the project. To reduce error probability, several experts perform this estimation and synchronize their results. The whole process is moderated by a coordinator.
The Delphi method model
Compile task lists
⬇️
Talk through task list with expert
⬇️
Expert estimation for each item on list
🔹
Check / Compare results
◻️
Result = Average of individual estimations
In Delphi method where do you derive the task lists?
The task lists in Delphi method is derived from the System specification or from a requirement document.
The items in the list should have adequate size, it shouldn’t be too small or too large. If it’s too small the estimation would be very difficult.
In Delphi method, the unit for effort estimation is
Person-days which is the amount of work that one person can do in one day.
Wideband Delphi method has
Additional step that allows experts to discuss unclear items.
What makes the Delphi method more time consuming
Anonymity.
It also makes experts to freely express their opinions.
Ratio of basic software engineering activities used by sd&m AG
- 30% Requirements analysis and system specification
- 15% System design
- 40% Implementation
- 15% Test & Integration
Implementation is relatively easy to estimate, to come up with the estimation of the total effort, we can just estimate the implementation effort and derive the remaining 60% afterwards
Overall effort = 100 / 40 = 2.5
Use this value to multiply the person-day value for implementation to get the overall effort.
Then for other sections of the pie = overall effort * % ratio
Testing and integration = overall effort * 15%
A practical way to reduce the size of a large list for a large system
is to apply clustering.
