CS605 Final Term Comprehensive Notes by Muhammad Saeed

Task Network

Since it is a concept development project, the applicability is not certain but it appears to be useful and hence needs to be explored. Major tasks include:

• Concept scoping
• Preliminary concept planning
• Technology risk assessment
• Proof of concept
• Concept implementation
• Customer reaction to concept

Defining a Task Network

Once the tasks have been identified, we need to develop a task network to determine the sequence in which these activities need to be performed. This will ultimately lead to the time required to complete the project.

Scheduling

Once we have the task network, we are now ready to prepare a schedule for the project. For this we use two techniques known as:

1. Program evaluation and review techniques (PERT)
2. Critical Path Method (CPM)

These are quantitative tools that allow the software planner to determine the critical path – the chain of tasks that determines the duration of the project and establish most likely time estimates for individual tasks by applying statistical models. They also help the planner to calculate boundary times that define a time window for a particular task. The boundary time defines the following parameters for a project:

• The earliest time that a task can begin when all preceding tasks are completed in the shortest possible time
• The latest time for task initiation before the minimum project completion time is delayed
• The earliest finish
• The latest finish
• The total float – the amount of surplus time or leeway allowed in scheduling tasks so that the network critical path is maintained on schedule

In order to use the PERT and CPM, the following is required:

• A decomposition of product function
• A selection of appropriate process model and task set
• Decomposition of tasks – also known as the work breakdown structure (WBS)
• Estimation of effort
• Interdependencies

Timeline Chart

To develop the schedule for a project, time required for each activity in the Task Network is estimated. This analysis and decomposition leads to the development of a Timeline or Gantt Chart for the project which portrays the schedule for the project. Concept Scoping (the first task in the above list) is further subdivided into the following sub-tasks

1. Identification of needs and benefits (3 days)
2. Definition of desired output/control/input (7 days)
3. Definition of the function/behaviour (6 days)
4. Isolation of software elements (1 day)
5. Researching availability of existing software (2 days)
6. Definition technical feasibility (4 days)
7. Making quick estimate of size (1 day)
8. Creating scope definition (2 days)

Project Tracking

Tracking methods include:

• Periodic project status meetings
• Evaluating the results of all reviews
• Determine whether project milestones have been accomplished by the scheduled date
• Comparing actual start date to planned start date
• Informal meetings with the practitioners
• Using earned value analysis

Earned Value Analysis

Earned Value Analysis or EVA is a quantitative technique for assessing the progress of a project. The earned value system provides a common value scale for every software task, regardless of the type of work being performed. The total hours to do the whole project are estimated, and every task is given an earned value based on the estimated percentage of the total.

SPI (Schedule performance index) close to 1 indicates efficient execution. Value of CPI (Cost performance index) close to 1 means project is within its defined budget. Therefore, by using SPI and CPI we estimate how the project is progressing. If we have these values close to 1, it means that we have had good estimates and the project is under control.

Error tracking can also be used to estimate the progress of the project. In this case we track errors in work products (requirement specifications, design documents, source code etc) to assess the status of a project. The process works as follows: We collect error related metrics over many projects and determine our defect removal efficiency in the following manner: Defect removal efficiency, DRE = E / (E+D), where

• E – errors found before shipment
• D – errors found during operation

It provides a strong indication of the effectiveness of the quality assurance activities.

Time Boxing

Time-boxing is used in severe deadline pressure. It is a use incremental strategy where tasks associated with each increment are time-boxed in the following manner:

• Schedule for each task is adjusted by working backward from the delivery date.
• A box is put around each task
• When a task hits the boundary of the box, work stops and next task begins

The principle behind time-boxing is the 90-10 rule (similar to Pareto Principle) – Rather than becoming stuck on the 10% of a task, the product proceeds towards the delivery date in 90% of the cases.

Software Quality Assurance

Software quality is defined as conformance to explicitly stated functional and nonfunctional requirements, explicitly documented development standards, and implicit characteristics that are expected of all professionally developed software. This definition emphasizes upon three important points:

• Software requirements are the foundation from which quality is measured. Lack of conformance is lack of quality
• Specified standards define a set of development criteria that guide the manner in which software is engineered. If the criteria are not followed, lack of quality will almost surely result.
• A set of implicit requirements often goes unmentioned (ease of use, good maintainability etc.)