For example, a client may want a new web site. But he doesn't really know what a good website for his business is. He just knows that his current one isn't working. But, until we know his business, we can't make a time or cost estimate. The bottom line is this: Before we can prepare a precise time or cost estimate, we must work with the client to define the scope of the project.
Estimation techniques for web projects / Emilia Mendes. p. cm. Summary: “This book provides a step-by-step methodology to improving cost estimation practices . Cost Estimation Techniques for Web Projects: Computer Science & IT Books.
In case the term "scope" is unfamiliar, it means "what we are making. There is a story that illustrates this last point. One time, there was a project to drain a swamp. A county executive asked, "how much will it cost to drain this swamp? This is the big problem with time and cost estimation.
We have to plan enough to know what the customer really wants, and do enough work on the project to discover what is really going on, before we can make an accurate cost estimate. But, often, the executives want an accurate cost estimate before the project is even started.
There's one more thing you're going to need, and I've written an article about it: An understanding of the key factors of good estimation of time, cost, or anything else. The amount of work it takes to make a good cost estimate depends on the size of the project you are doing, and also on how familiar you and the team are with project work. And the same techniques, applied carefully with a lot of research, can be used to estimate projects that will cost millions of dollars.
But that will take months of work, and a lot of other useful project planning will go into the cost and time estimate. Because we are focusing on the techniques, we will work with a very simple, small project: The first web site for a new startup company, including 40 pages of text and graphics, and a shopping cart with about products.
A print catalog with all product images and descriptions has already been done. But the company does not like the catalog layout, and needs a new artwork and concept design for the web site, which it will also use for future print marketing. As we have already said, the earliest cost estimate must come after the project scope is clearly defined, an approach to the project is agreed on, and assumptions are clarified.
When this is done, but we do not yet have a step-by-step plan for doing all the work, we can create an early cost estimate. An early cost estimate is called an order of magnitude cost estimate by the Project Management Institute. When we create it, we provide a range in which we are almost certain that the cost of the project will fall. But it is a pretty big range. When we deliver an estimate with such a big range, the project sponsors will probably go ballistic. Most project sponsors want, and need, a much more precise estimate much earlier than is possible. It takes educating upward, that is, teaching our bosses what is realistic, to help them understand that an order of magnitude estimate is the best that even the best project managers in the world can do, early in a project, before the plan is nearly complete.
At this stage, there are simply too many unknowns to make a more realistic guarantee. You will probably get everything you want. If not, you'll get the three or four most important things, and we can do the last one or two on next year's budget.
Most projects can be broken into a few big pieces, and estimates put together from pieces are always better than estimates created from the project as a whole. So let's look at the pieces of the web site project in our example. We will include:.
Our first step is to figure out the best way to get a cost estimate for each of the five parts of the project listed above. For items one, two, and five, our best solution is to create an estimate based on the actual cost of doing the same things for similar sites for past customers. For item 1, we can probably even lock down a fixed price.
On item 2, we talk to the graphic artist. He may say, "Well, it depends. If they know the general style of the business, and they like my first ideas, that's one thing. But if they have no idea what they want, and they have a committee making decisions, and then they start changing the names of their product lines while I'm doing the graphics, it could cost a lot more.
But let's say we don't. Then we ask the graphic artists to estimate the cost for the best case and worst case scenarios, and those are our low and high estimates. Items 3 and 4 are best estimated using the Bucket Method. But the method described for items 1, 2, and 5 will also work. Item 5 is similar to item 2. For example, if all sales are in the Continental US, then testing a shopping cart is standard. If you international shipping is needed, along with international taxes and tariffs, a lot more testing will be required.
In this case, we went to the client and they said, "Oh, we're in the US and only selling in the US right now. So we got a pretty narrow range of low and high in our estimate for going live, as you see in Table 1.
This method puts together a good early time and cost estimation. The cost estimate is illustrated in Table 1. The time estimate is created in a similar fashion, asking each worker or team leader for a low, likely, and high estimate of how long the work will take, and the estimates are added together. A key advantage of this approach is that, even if one part is estimated too low, another part is likely to be estimated high. So the total estimate has a greater chance of being right than any one part.
This is the major reason for breaking a project into parts and estimating each one separately, instead of trying to estimate the entire project all at once. How accurate is our estimate? That varies a lot, by industry, and also by other project and team factors. A bid that is too high won't get the contract, and a bid that is too low will mean financial loss for the company.
Construction projects can be estimated so precisely because methods, materials, and costs are very standard. On the other hand, information technology IT projects are notoriously badly estimated.
Separate screens that are displayed. Having a buffer in the estimation enables to cope for any delays that may occur. How accurate is our estimate? Each major processes can be decomposed into smaller processes. It is difficult to estimate SIZE in the early stage of development. Download this guide.
But actual results ending up double or triple the estimate for time or cost is far too common. One reason for this is that tools, techniques, and environments change rapidly in the IT world. It even happens that a program is written, say, for one version of Windows, then has to be rebuilt for another version of Windows before it is released.
How do we make the best estimates we can in our own industry? Consistent, complete project management planning and tracking and a lessons learned to improve our methods at the end of each project are key. And, when doing each estimate, ask, "How familiar is my team with this exact type of work? Have we ever worked together before? What is new and different on this project? And, at the same time, when you are estimating work using new tools and methods, or developing experimental prototypes, or working with new clients, take that into consideration, and allow more leeway for the unexpected.
Later in the project planning process, we can create a much more accurate estimate. And it is a lot easier to do, as well.
The PMI calls late time and cost estimation bottom-up estimation, because we estimate each detailed activity, and add them all up to get a total. And schedule variance is the same. If a project is expected to run for days from beginning to end, then it is very likely to run between 90 and days. That smaller range is much easier for the project sponsors to work with. Ideally, the detailed cost estimate will be part of a complete project plan, in which all nine areas of project management knowledge are addressed, as described in the article I listed above, How to Layout a Project Plan.
With all this information available, creating a detailed cost estimate is quite easy - in fact, it is easier than creating an early estimate. We simply add up the cost time and materials for each activity of the project, and come up with a total. As part of this process, we can use a PERT estimate.
PERT stands for Project Evaluation and Review Technique, and it is a way of getting a single cost estimate using a centering average of optimistic, likely, and pessimistic estimates for each line item. Actions Shares. Embeds 0 No embeds. No notes for slide. Web Engineering - Web Effort Estimation 1.
With the sheer diversity of Web application types and technologies employed, in order to make the Project successful, we need to estimate cost, effort, budget, resources, schedule etc. It has been and still is widely used in software and Web development. However, studies show that this technique can be an effective estimating tool when used in combination with other less subjective techniques e.
Such techniques attempt to formalize the relationship between effort and one or more project characteristics. The central project characteristic used in such a model is usually taken to be some notion of software size e. This formalization is often translated as an equation such as that shown by Eq. Step 1 is used only once to calculate the initial values for its parameters, which are then fixed from that point onwards.
The single use of step 1 makes this model a generic algorithmic model.