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Editors' Choice Article Estimating Time Accurately Establishing Realistic Project Timelines | |||||||||||||||||||||||
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For instance, they may not take into account unexpected events or urgent high priority work; and they may fail to allow for the full complexity of the job. Clearly, this is likely to have serious negative consequences further down the line. This is why it's important to estimate time accurately, if your project is to be successful. In this article, we look at a process for making good time estimates, and we explore some of the estimating methods that you can use. Why Estimate Time Accurately? Accurate time estimation is a crucial skill in project management. Without it, you won't know how long your project will take, and you won't be able to get commitment from the people who need to sign it off. Even more importantly for your career, sponsors often judge whether a project has succeeded or failed depending on whether it has been delivered on time and on budget. To have a chance of being successful as a project manager, you need to be able to negotiate sensible budgets and achievable deadlines. How to Estimate Time Accurately Use these steps to make accurate time estimates: Step 1: Understand What's Required Start by identifying all of the work that needs to be done within the project. Use tools such as Business Requirements Analysis, Work Breakdown Structures, Gap Analysis and Drill-Down to help you do this in sufficient detail. As part of this, make sure that you allow time for meetings, reporting, communications, testing and other activities that are critical to the project's success. (You can find out more on these activities in our article on Project Management Phases and Processes.) Step 2: Order These Activities Now, list all of the activities you identified in the order in which they need to happen. At this stage, you don't need to add in how long you think activities are going to take. However, you might want to note any important deadlines. For example, you might need to get work by the finance department finished before it starts work on "Year End." Step 3: Decide Who You Need to Involve You can do the estimates yourself, brainstorm them as a group, or ask others to contribute. Where you can, get the help of the people who will actually do the work, as they are likely to have prior experience to draw upon. By involving them, they'll also take on greater ownership of the time estimates they come up with, and they'll work harder to meet them.
Step 4: Make Your Estimates You're now ready to make your estimates. We've outlined a variety of methods below to help you do this. Whichever methods you choose, bear these basic rules in mind:
Methods for Estimating Time We'll now look at different approaches that you can use to estimate time. You'll probably find it most useful to use a mixture of these techniques. Bottom-Up Estimating Bottom-up estimating allows you to create an estimate for the project as a whole. To analyze from the "bottom up," break larger tasks down into detailed tasks, and then estimate the time needed to complete each one. Because you're considering each task incrementally, your estimate of the time required for each task is likely to be more accurate. You can then add up the total amount of time needed to complete the plan.
Top-Down Estimating In top-down analysis, you develop an overview of the expected timeline first, using past projects or previous experience as a guide. It's often helpful to compare top-down estimates against your bottom-up estimates, to ensure accuracy.
Comparative Estimating With comparative estimating, you look at the time it took to do similar tasks, on other projects. Parametric Estimating With this method, you estimate the time required for one deliverable; and then multiply it by the number of deliverables required. For example, if you need to create pages for a website, you'd estimate how much time it would take to do one page, and you'd then multiply this time by the total number of pages to be produced. Three-Point Estimating To build in a cushion for uncertainty, you can do three estimates - one for the best case, another for the worst case, and a final one for the most likely case. Although this approach requires additional effort to create three separate estimates, it allows you to set more reasonable expectations, based on a more realistic estimate of outcomes.
Preparing Your Schedule Once you've estimated the time needed for each task, you can prepare your project schedule. Add your estimates to the draft activity list that you produced in the second step, above. You can then create a Gantt Chart to schedule activities and assign resources to your project; and to finalize milestones and deadlines.
Key Points You need to estimate time accurately if you're going to deliver your project on time and on budget. Without this skill, you won't know how long your project will take, and you won't be able to get commitment from the people required to help you achieve your objective. More than this, you risk agreeing to impossibly short deadlines, with all of the stress, pain, and loss of credibility associated with this. To estimate time effectively, follow this four-step process:
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A Final Note
Learn how to estimate time accurately, and you'll be well on your way to being seen as a successful, effective, and reliable project manager. Plus your projects will be more enjoyable, and your team will be a lot less stressed! Next week we're exploring influence and persuasion - these are important skill areas, and they're incredibly useful in many workplace situations. See you then, and have a great week!  James Manktelow Email us Mind Tools Essential Skills for an Excellent Career! |
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