As Test Manager I fit my team's work into multiple overlapping project schedules which are not under my control. The schedules have, as you might expect, multiple constraints that operate simultaneously, such as:
- end dates or other milestones
- dependencies on other parts of the schedule or other schedules
- level of effort we are able or prepared to commit to different tasks in absolute terms (e.g. contractually) or in relative terms (e.g. based on perceived risk)
- methodology; different teams in Linguamatics operate different development methodologies, and we work with non-development teams too
- desired quality level (whatever that means in any given case)
To do my best to provide the service my (most often internal) clients want - which generally includes some kind of estimate, even if there is little at times to base it on or anchor it to - I think I need a few things, including some model of:
- the resources that I have or will have available
- the status of the projects that are ongoing
- the relative importance of projects to one another
- transparency of decision-making
- clarity of current priorities
- visibility of actions aimed at improvement
For most projects that we decide to track, the tester or testers on a project, and/or me, will pick some initial budget. (There are some exceptions which I'll touch on later.) The budget is based on all sorts of factors, such as those mentioned above and those summarised by George Dinwiddie in Estimating in Comparison to Past Experience and attempts to take uncertainties into account.
I view the budget as a kind of "top-down" number. It (a) fits into and influences the global scheduling and (b) provides implicit guidance to the testers about the time they have available to test given what we know now. It is part of the project context for them, and should constrain testing in the way that other aspects of that context do.
As work proceeds, testers report the time spent on each project along with their current estimate for the remaining work. I view this as a "bottom-up" number. It (a) invites the tester to think at a level higher than immediate action, to step back, to defocus, to prioritise and (b) provides feedback to me and the bigger scheduling headache.
Some projects are more top-down: for example a piece of work which is set up in a time-box. Some projects are open-ended and bottom-up: for example an investigation into a live support issue. Most projects sit somewhere in between. Projects which are entirely bottom-up will often start with a phase where no explicit budget is set and no estimate is made; instead we'll just record time spent. At some point we'll either reach the end of the investigation, the end of the availability of the tester (in which cases work stops) or some point where we feel we understand enough to set a budget.
Because many of our projects tend to be more schedule-bound, our default position tends to be to assume that project work consumes the budget and then stops and that the tester will reprioritise based on this as necessary. However, frequently something happens on a project that affects the tester's estimate - the feature turns out to be more solid or less complex than we expected; we were able to do more work in unit testing than we anticipated; there's some horrible interaction with another piece of our application that no-one expected. In this case, we will talk about the current budget and the differences between it and the new estimate and what impacts there would be of changing the budget, or not. Some for-instances:
- the tester discovers that there's some area we didn't think needed testing but actually does and increases their estimate to accommodate it. I might decide, on a schedule basis, that more time is not available, so the budget does not change, and the question becomes one of balancing risk inside the existing budget. Future estimates for this project will need to take this decision into account.
- the tester discovers that the implementation is missing some behaviour that the company deems is critical. It will require investigation and retest so they increase their estimate to accommodate that work. I agree that this is important and we increase the budget to provide more time. (And I deal with the global scheduling impact.)
- I find that there is more time in the schedule, perhaps because something else got cancelled. I tell a tester who previously wanted time for some piece of work that is it now available and increase the remaining budget for that work.
- I am told that we need to complete work on some project earlier than previously understood and I reduce the budget on it, prompting a discussion about how best to proceed (with the usual iron triangle to constrain us).
The budget and and estimates mutually constrain one another and contribute uncertainties at their different granularities. They mix science and instinct, planning and gut; known and unknown; they're guesstimates. They go well together, they bounce off each other, they influence one another and reflect one another, they're like best mates; they're bestimates you might say, although I never do.
In some sense I think of them as a simple interface between the complexities at the test level and complexities at the management level. Compressed down into a single number they naturally lose information but, when more information doesn't need to be shared (essentially we are on-track relative to the most recent conversation), that is sufficient and indeed efficient. Having a communication channel open for when more needs to be shared is, as I've just said, crucial. And I'll say it again: available channels of communication are absolutely crucial.
NotesThe approach described is a high-level sketch of the process that has evolved over time to try to manage competing constraints and requirements of the kinds that I mentioned at the top. And it continues to evolve to meet new constraints or ideas. If it stops meeting my needs, I'll stop using it.
We use the same spreadsheet and reporting mechanism to record time spent on ongoing team-level tasks which we then use to project future levels of effort, or identify trends or that there may be a problem we need to look into.
What I've written here leaves out a lot of detail in and around what we do, including how we decide what work to do in any given case, the existence of peer review (so there are other eyes on the work), the help I get from my team in spotting bugs in what I've done, questioning why I do it - which is how this particular post came about - or suggesting improvements, the importance of trust on both sides, and the importance of testers being empowered and supported in their work.
Edit: David Hansson of Basecamp covered some similar ground in Drive Development With Budgets Not Estimates.