Psychologists have an actual term for humans being bad at estimating. The term “planning fallacy” was coined by psychologists Daniel Kahneman and Amos Tversky in 1977. The premise is that people tend to make two key errors, which lead to inaccurate estimates. The first error, people tend to ignore historical data. Second, people fail to plan for the unexpected.
The first fallacy in estimation, failing to consider historical data, concerns me the most. I personally believe the key to be exceptional at estimating is experience. If one ignores historical data, then experience is negated from the equation. The second is an understandable challenge. The unexpected is exactly that, so one can never perfectly plan for it.
In my estimation methodology, I will work to address both fallacies. The steps in the estimation methodology are simple, yet most people jump right in, and miss key steps:
- Define the scope of the project or tasks that you are estimating.
- Make a detailed list of tasks.
- Identify both external dependencies and internal dependencies.
- Review each detailed task and mark the following:
- Degree of difficulty (high, medium, low)
- Amount of experience you have with completing a task of this nature (none, some, substantial)
- Potential unknowns – what could derail this particular task?
- Estimate each individual task.
- Add buffers for tasks with dependencies, minimal past experience and significant potential unknowns.
- Total your estimate.
- Map your estimate out on a calendar.
- Begin your effort, reviewing your estimate on an ongoing basis and tracking actuals to your estimate.
- Learn from your experience.
Today, we cover step 1, define the scope of the project or tasks that you are estimating.
Exactly what does the estimate entail? The first step in effectively estimating, is defining what needs to be done, also known as the scope of the tasks that one is estimating for. Every solid estimate consists of both a list of things that will be done, and a list of assumptions that includes things that will not be done. For example, let’s say that you are putting together an estimate for the time that it will take to remodel your kitchen, you would want to clearly decide what all you are going to do. Painting the cabinets might be part of the project, but you are not planning to paint the insides. That should be specified in your estimate as painting the inside would likely more than double the timeline.
An approach to effectively defining the scope is to begin with the high level goal or objective, and then work backwards. To do this, define what the end state will look like. In the example of your kitchen remodel, what do you want the kitchen to look like? Can you accomplish your desired end state in a single effort, or should you break the work out into phases?
The more detail you put into your scope, aka what you want to accomplish, the more effective you will be at estimating. The key components of the detail scope are:
- An explanation (justification) of why the work should be done
- A clearly defined project objective and description
- The deliverables described in detail
- A clear declaration of what is not in scope
- Constraints that could impact the delivery of the project
- Assumptions that you made in defining the scope. The assumptions bake directly into your estimates.
For estimating smaller projects or tasks, one will want to move quickly through these seven components of their scope, but one should always consider these things when providing an estimate.
In our next blog we will discuss step 2 – “Make a detailed list of tasks”. In the meantime, you can find more career coaching and join your fellow MyBlankJob users in discussions on all of the workplace challenges, including providing estimates – Workplace Rants | My Blank Job.