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Estimating is hard enough. It is even
harder if you are not prepared. Estimating a 20 hour chunk of work is
not so hard. Estimating for full projects or large chunks of work can be
challenging.
Templates can help, but consider the following steps before
you begin the estimating process.
Get a clear picture of the work that
is being estimated
Many problems with estimation come because
the estimator is not really sure what the work entails. You should
avoid estimating work that you do not understand. This should not
imply that you can know every detail. The estimating contingency
is a way to reflect some of this remaining
uncertainty.
Determine who should be involved in
the estimating process
The project manager may or may not know
enough to make the estimates on his or her own. It is usually a good
practice to look for estimating help from team members, clients,
subject matter experts, etc. This will usually result in the
estimates being far more accurate than you would get by yourself.
Determine if there are any
estimating constraints
If there are estimating constraints, it
is important to know them up-front. For instance, the end-date may
be fixed (timeboxed). You should also know if the client expects
Six-Sigma level quality in the deliverables, or if the 80/20 rule will
apply. It is possible that there may be a fixed budget that cannot
be increased. (This would be of interest so that you can reduce the
scope of work, if necessary, to meet the fixed budget.) Knowing
these constraints will help the estimators make valid assumptions
regarding the cost, duration and quality balance.
Determine multiple estimating
techniques to utilize if possible
There are a number of
techniques that can be used to estimate work. If possible, try to
use two or more techniques for the estimate. If the estimates from
multiple techniques are close, you will have more confidence in your
numbers. If the estimates are far apart, you need to review the
numbers to see if you are using similar assumptions. In this case,
you can also try to utilize a third (and fourth) estimating
technique to see if one initial estimate can be validated and the
other rejected.
Document all assumptions
You
will never know all the details of a project. Therefore, it is
important to document all the assumptions you are making along with
the estimate.
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