Class Act in Parallel Programming [Bookshelf]
QUANTIFY UNCERTAINTY. The final reason that project teams say they can’t estimate is that all these numbers are uncertain. Source lines of code, for instance, is an inexact indicator of a product’s functionality. This uncertainty leads many software people to throw up their hands, look skyward, and bleat, “We just do the best we can down here in the boiler room.” Statistics was invented to cope with uncertainty. As a software developer, you have enough on your plate without having to master statistics, but the basics are not that difficult. uncertain, then the process productivity, derived from these three, is going to fall within a range, not on an exact point. If the estimate of the next project’s size, even ifyou wait until the end of the risk-reduction stage, is imprecise, then the estimate for the next project is going to be a range, not an exact number of dollars. Of course, the people with cigars want a quote to the exact dollar. Not to worry. This is where statistics comes in. It can tell you something like this. There is a 50percent probability that you can complete this project successfully in x months withy person-months of effort applied. Bidding on this basis, over the next dozen or so projects, your organization ought to break even. Some would lose money. Others would make money. You can raise that 50-percent probability to 7 5 percent, or even higher, up into the 9 0 s b u t you cannot realistically get to 100 percent. If you must bid low sometime, you can lower your estimate. If If the counts of source lines of code, person-hours, and months’ duration are a little you do that, you will probably lose money on that particular job, but then you expected to. In the longer range, you can submit most of your bids in the 60 to 70 percent range and confidently expect to make some money over the next dozen projects. “All that’s a very tall order,” we hear you say as you peer anxiously through the cigar smoke. “Sure it is,” we reply. “Still, a few companies make it work and get good commercial results. Do you want them to get all the business?” +