Estimate Don't Guesstimate
When planning a project accurate estimates are key to a realistic plan. However, many estimates are no more than guessing. Sometimes it simply is not possible to provide an accurate estimate because the project involves tasks that have never been done before so there is no historical data to draw upon. But often, even when there is some reliable data, it is not used to produce a good estimate.
It is difficult to know exactly why this happens. Some people may have not had direct experience of producing proper estimates for tasks and it's fair to say there may be some wishful thinking on the part of the stakeholders influencing the "estimates".
So What Is Estimating?
Estimating means reviewing various pieces of information to get a good idea of what the answer to a question may be. So the answer to an everyday question might be - how long will it take me to get to X next week? In which case the answer can come from past experience, rough guide times found online and various other factors like the time of travel (rush hour etc). So you can never have an exact answer, but an estimation which is based on various pieces of sound information - this is not just a guess.
When it is impossible to get an exact answer to a question, we estimate the answer, and for many project tasks this is the best accuracy we can hope for. We use as much information as possible relating to the task to get the most accurate answer for the initial planning stage. Of course, any experienced project manager will know that time and cost estimates can, and do, change but the more information used to determine the estimate, the less it should vary from the real figures.
Basic rules for getting an initial estimate:
- What is the task?
- What are the variables?
- Collect data in as much detail as possible or as needed
- Make an estimate
- Provide evidence to back up the estimate to remove any chance of reference bias
By following these simple rules you can learn to create reliable estimates and use them within your project to help better manage time and budget.
There are lots of myths associated with estimation, which can be detrimental to your project plan and you may encounter various difficulties when you try to use proper estimation techniques within a project. Perhaps senior management bypass the estimates you make, or they simply don't believe your estimates. Or perhaps you get asked to create estimates without any information to base them on. In these instances it should be a priority to open up a line of communication that enables you to gain the information you need.
Some people, even project managers, treat estimation as rough guesswork themselves, especially if they know there will be large discrepancies between the real and estimated figures. Others simply add huge contingency amounts to make up for the lack of knowledge or understanding of the tasks. Sometimes thos people who could provide the information simply don't take the estimation process seriously so they might not provide you with the relevant information. In all instances, the more communication the better. The sooner you can create excellent estimates backed up by sound data, the sooner those around you will learn to take the estimation process seriously.
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