Estimating Software Projects


Related Links FP Training Public Training Courses Free Stuff University Programs Online Library Client List Public Speaking FP Public Training		Self Pace Online Function Point Trainingting Software Projects Introduction When I speak at a conference, workshops or training sessions, I often begin by asking three questions. How many of you have worked on software projects delivered over budget and late? - nearly everyone will raises their hand. How many of you have worked on a software project that was on time? - a few people will raise their hands. How many of you have worked on a software project that was delivered early and under budget? The normal response is laughter. Software professionals are very weak at estimating. This article provides some data that can be used for estimating purposes. Additionally, the article outlines some basic data for estimating. The article Estimating Software Projects also on this website provides even more tips on how to estimate software projects. How does size impact productivity As the size of software development project becomes larger the cost per function point actually rises. As can be seen from the graph and data, the effort per unit does not remain constant as the size of the software project increases. This is self-evident because the tasks are not the same for software projects as the size increases. Like other large construction projects there is an increasing marginal cost for software development projects. What is Marginal Cost? As some of you remember Marginal Cost is an economic term and is different from average cost. Average cost is the total cost of producing a particular quantity of output divided by that quantity. In this case to Total Cost/Function Points. Marginal cost is the change in total cost attributable to a one unite change in output. In our case, how does per unit cost change as the software project size change. Imagine the average cost per square foot of a one story building compared to the cost per square foot of a 100 story building. No doubt the construction costs (per unit cost) for the 100 story building are much higher than a one story building. These same concept is true for a software project. Why increasing Marginal Costs for Software Development? There are a variety of reasons why marginal costs for software increase as size increases. The following is a list of some of the reasons As size becomes larger complexity increases. As size becomes larger a greater number of tasks need to be completed. As size becomes larger there is a greater number of staff members and they become more difficult to manage. Since fixed costs for software projects is minimal. There are little if any economies of scale for software projects. Why is this data useful? In the absence of your own data the following table can be useful. The item that impacts productivity the most is the size of the project. It is interesting to note that nearly 75% of projects over 8,000 function points will fail and/or be canceled. If you have your own data, it is important for your organization to understand what impacts productivity. Besides being able to calculate total hours from the following chart it is important to understand some basics regarding estimating. Source of Data Over the past seven years of consulting I have gathered data from over a 100 different companies and nearly 1,000 different projects. Additionally, I have collected data and information from surveys and other studies. There are two other articles that may be interesting for you to read Estimating Software Projects and Estimating Defects and Test Cases. Lines of code estimating: A site on using lines of code managed by James Heires. http://www.jamesheiresconsulting.com To see other full articles click here. We often post new articles and information. Please send an email and we will send notifications when new information is posted. Online Function Point Trainngma Copy and reproduction is permitted if following appears on all pages.

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	For more information: Knowledge@SoftwareMetrics.Com Longstreet Consulting Inc. 2207 SW Walnut Blue Springs, MO 64015 voice: 816.739.4058 or David Longstreet direct at David@SoftwareMetrics.Com copyright: Longstreet Consulting Inc. 1992-2008


Software Estimating Training Class