2008-09-24 08:43:54
At the initial planning stage the main objective is to get a realistic estimate
of the time involved in the project. You must establish this not only to assist
higher management with their planning, but also to protect your team from being
expected to do the impossible. The most important technique for achieving this
is known as: guesstimation.
Guesstimating schedules is notoriously difficult but it is helped by two
approaches:
down structure and look for the longest path through the sequence diagram
skills
The corollary to this is that you should keep records in an easily accessible
form of all projects as you do them. Part of your final project review should
be to update your personal data base of how long various activities take.
Managing this planning phase is vital to your success as a manager.
Some people find guesstimating a difficult concept in that if you have no
experience of an activity, how can you make a worthwhile estimate? Let us
consider such a problem: how long would it take you to walk all the way to the
top of the Eiffel Tower or the Statue of Liberty? Presuming you have never
actually tried this (most people take the elevator part of the way), you really
have very little to go on. Indeed if you have actually seen one (and only one)
of these buildings, think about the other. Your job depends upon this, so think
carefully. One idea is to start with the number of steps - guess that if you
can. Notice, you do not have to be right, merely reasonable. Next, consider the
sort of pace you could maintain while climbing a flight of steps for a long
time. Now imagine yourself at the base of a flight of steps you do know, and
estimate a) how many steps there are, and b) how long it takes you to climb
them (at that steady pace). To complete, apply a little mathematics.
Now examine how confident you are with this estimate. If you won a free flight
to Paris or New York and tried it, you would probably (need your head examined)
be mildly surprised if you climbed to the top in less than half the estimated
time and if it took you more than double you would be mildly annoyed. If it
took you less than a tenth the time, or ten times as long, you would extremely
surprised/annoyed. In fact, you do not currently believe that that would happen
(no really, do you?). The point is that from very little experience of the
given problem, you can actually come up with a working estimate - and one which
is far better than no estimate at all when it comes to deriving a schedule.
Guesstimating does take a little practice, but it is a very useful skill to
develop.
There are two practical problems in guesstimation. First, you are simply too
optimistic. It is human nature at the beginning of a new project to ignore the
difficulties and assume best case scenarii - in producing your estimates (and
using those of others) you must inject a little realism. In practice, you
should also build-in a little slack to allow yourself some tolerance against
mistakes. This is known as defensive scheduling. Also, if you eventually
deliver ahead of the agreed schedule, you will be loved.
Second, you will be under pressure from senior management to deliver quickly,
especially if the project is being sold competitively. Resist the temptation to
rely upon speed as the only selling point. You might, for instance, suggest the
criteria of: fewer errors, history of adherence to initial schedules, previous
customer satisfaction, "this is how long it takes, so how can you trust the
other quotes".