How Long is a Piece of String?
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It's a common question and one I've occasionally used in reply
when asked "We are building this new thing. How long
will it take to provide some documentation for it?"
Estimating the amount of time it takes to write documentation is
tricky because it relies on many differing, subtle factors. For
many people working outside of a highly regimented, project-managed
team, it tends to boil down to a mixture of guesswork and experience.
However, it's not impossible to come up with a more reasoned estimate
as long as you don't mind doing a little planning. Although, to
be frank, if you aren't planning your work, you can probably stop
reading now and go find a copy of JoAnn T. Hackos' Information
Development: Managing Your Documentation Projects, Portfolio, and
People.
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A Tool for Estimating
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So in the spirit of sharing, I present an estimating tool I've
used in the past and have, very recently, uncovered again. This
tool is based on JoAnn Hackos' dependencies calculator (see her
book, Managing Your Documentation Projects, in the section
about "Making a Preliminary Estimate of Required Resources").
I've adapted my tool for use with single source content but you
can also use it for other types of documentation projects.
The idea is simple enough. You break down your planned content into
topics, with a topic defined as a discrete amount of information
that shouldn't take more than a couple of hours to write. Then,
when you add in time for review and rewrite, you can take an educated
guess as to how long an average topic* takes to complete. So, for
the sake of discussion, let's say an average topic takes about five
hours to complete. Each topic is then scored against four criteria,
with the scoring used to add or subtract an appropriate level of
variance, as follows:
- Difficulty of topic — Do you know what you are writing
about or is it brand new? Is it a simple topic or something complex?
- Scope of topic — Does the difficulty dictate that a lot
of content is needed? Or is it a short topic of fixed content?
- Availability of information — Are you updating an existing
document? Do you have a specification to work from? Or do you
have to write from scratch?
- Access to SME — Do you have good access to a Subject Matter
Expert? Do you have limited access only or none at all?
* Defining an average topic is probably the most contentious
part of this method and it may take some refinement to arrive at
a workable number.
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Calculate Topic Complexity
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Each topic is scored from 1 (long, hard, complex) to 5 (short,
easy, simple), against each criterion. An average topic would score
3 for each criterion and won't affect the estimate from the standard
five hours. Scoring the topics this way allows you to factor in
a level of variance. A difficult topic with a large scope that has
no information available, and for which you have no access to an
SME, will score lowest marks (all criteria score 1) and has the
highest level of variance from your standard topic estimate.
The criteria are fairly high level, and you could certainly expand
on these for a more granular approach, but I've found that most
issues can be assigned to one of the above criteria and that keeps
the estimation as simple as possible. The variance can then be calculated
(again, with an estimated time) so that you can adjust the time
it takes to complete the topic. For example:
Score 1 — Variance of +2 hours per criteria
Score 2 — Variance of +1 hour per criteria
Score 3 — Zero variance
Score 4 — Variance of -30 minutes per criteria
Score 5 — Variance of -1 hour per criteria
The figures given above are, also, estimated. You'll note that
the higher scored (and therefore lower variance) topics don't gain
you proportionately the same amount as you lose to the lower scored
(higher variance) topics. The reality is that, no matter how simple
the topic, it still takes time to document.
A long, complex and difficult topic with little to no information
and no available expert will score 1 across the four criteria and
add 8 hours (2 hours per criteria) to the estimated completion time
for that topic, taking the estimated total for that topic to 13
hours.
Flip the example around so that you are estimating a short, simple
topic, which comes with sufficient supporting information and an
SME sitting on your desk to help you write it. That topic would
score 5 for each criterion, and gain you 4 hours, meaning the estimated
total for that topic would drop to 1 hour. (It is interesting to
note that increasing the gain numbers enough could result in a topic
taking less than zero time to create!)
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Use My Spreadsheet to Aid Calculations
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Now, the obvious thing to do would be to create a spreadsheet that
allows you to add in your topics, score them against the criteria,
and calculate the total estimated time-and perhaps while it's at
it, add in a level of contingency. And that is exactly what I did.
Feel free to download the estimation
spreadsheet (zipped Excel file). It is annotated to help you
understand its use, and includes two additional columns which allow
tracking when a topic was added to the spreadsheet, either as part
of the initial planning, when identified during the review cycle,
or because of a change in product scope. All of the calculations
use basic arithmetic, so feel free to poke around and try this out.
My tool is not an exact system, but that's why they are called estimates.
If for nothing else, the tool helps my team plan what they are writing
about, which, sometimes, is more valuable than the estimates themselves.
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