Good estimates tell you how long a project task will take, but not everyone knows how to accurately estimate their own work Worse still, some members of your team think they are solid estimators, but never seem to deliver as promised.
There are many reasons why there is such variability in estimating project tasks, from inexperience to optimism. These 6 steps will help you get great estimates from your team every time.
1. Identify the Tasks to Estimate
Tasks help you plan accurately and build a reliable project schedule. Take a look at your project task list and identify which tasks need estimates.
Strip out all the routine tasks like project meetings or workshops as you can put them on the schedule for a particular day.
Remove anything that you know you can get precise estimates on. There’s no need to go through the process of estimating if you know that it takes 3 weeks to paint an office because you’ve done it a dozen times already.
All the other tasks will need someone to work out the time it will take to complete the task. That’s likely to be the majority of tasks on your To Do list.
2. Identify the Team Experts
Each task on your list will have someone allocated to do the work. This is probably the right person to prepare the estimate – but not always.
Sometimes it’s prudent to involve others in creating the estimate, especially if the person responsible is junior, new to the company or hasn’t done the activity before. Get someone with experience to help them craft the estimate. Your ultimate aim is to train the individual in how to estimate well, so give them every chance of success with an expert helping hand.
You may also want to involve managers or other teams, especially for complicated tasks. You could also bring in someone who did the same task on a similar project – while they aren’t allocated to your project they’ll have a great insight into how long it takes to do that sort of work.
Identify who will create your estimates for every project task. Then group tasks together by resource so you can hold estimating meetings with the right people and focus on their sections of the project.
3. Review Estimating Techniques
Before you involve the team it’s a good idea to refresh your memory on the different ways that you can create task duration estimates. Having an idea in mind when you start to talk to your team will help you guide them to the right technique.
There are a number of ways to estimate how long a task will take. Here are some options:
Professional judgement. Use the subject matter expertise of someone on the team who knows a lot about the task. They can tell you how long it will take based on their professional opinion and prior experience. This doesn’t have to be someone internal: if you don’t have the skills in-house then you can call in a third party expert and use their input.
Historical data (aka analogous estimating). Base your estimates on the results of a previous project. If your company did a similar project in the past and you can access the actual time taken for similar tasks, then that will give you a very good idea of how long the same task will take this time. Again, if you don’t have that knowledge in-house, there may be partner companies or published industry data that you can draw on for the same result. This type of estimating is quick and easy but you’re not going to get hugely accurate results.
Statistical analysis and math (aka parametric estimating). Bet you thought you left math in school, right? If the task you are estimating is relatively straightforward and repetitive you can use simple math to calculate the overall activity duration. For example, if it takes one person one hour to dig a hole and you need ten holes, then it will take ten hours of work. If you double the resources and have two diggers, it will only take five hours. If you bring in a machine which works at double the speed of a person, it will only take two and a half hours, plus an hour to fire the machine up in the morning. Don’t forget to add in time for tea breaks!
Working from a range (aka three-point estimating). Hedge your bets with this technique. Work out the most likely, best case and worst case timescales for the task. Then there’s more math to do: add together the durations for the best and worst case, plus four times the most likely. Then divide by six. That gives you an estimated duration which takes into account the uncertainties of estimating but weights the result more heavily towards the most likely outcome.
Here’s the equation:
Best case (O, for optimistic)
Worst case (P, for pessimistic)
Most likely (M, for…. Most)
(O + 4M + P) /6
This is a good way of balancing the opinions of several experts in the team who all feel that they know how long it will take.
As a group. Another way to include multiple voices in the estimating process is to use the wisdom of the team. Discuss the problem and the activities involved together and draw an estimate from the results of that conversation. This is not particularly scientific but it can be a good way of gaining consensus, especially if you don’t have experience of doing this sort of work already.
Pro Tip: Whatever technique you decide to use, be clear about whether your estimates will include contingency time or not. If not, remember to add it later otherwise you won’t have any contingency!
4. Choose the Right Approach
Now you’re ready to involve your team members in creating the estimates. Talk them through the different techniques and have them suggest the right approach for each activity. Different approaches work well for different tasks – for example, you can’t use historical data to estimate if there is none, and if no one in the company has worked on a similar project, then your access to subject matter expertise is limited (although you could use a third party).
Create your estimates using your chosen techniques. Let task owners take the lead for the estimating process and step in as needed for any technical guidance. At the end of this step you’ll have task estimates for all your project activities.
As your goal is to boost the estimating skills of your team, it can be useful to use two (or more) different ways to estimate one task. Compare the estimates you get and make a judgment about which one you want to use on the project. Keep a note of the other estimates you came up with for the task as they will come in useful later.
5. Create the Project Plan
Use the task duration estimates created in the last step to update your project plan. Assign a task duration to every activity and update your schedule with any additional information such as if the task owner has changed as a result of the work done to date.
When all your tasks have durations you will be able to work out the overall length of the project.
6. Track the Accuracy of Estimates
Creating estimates is only part of the story. Once they are done, you want to continue to build your organizational knowledge by monitoring the accuracy of the estimates to see how well your team did at estimating the task durations. You can also monitor whether a particular technique for estimating worked best for your team, or for different types of tasks.
To do this, you need to know how long the task took when the team completed it. Track the actual hours spent on a task using time sheet data. Then compare this to the estimates (both the estimate you actually used and any other estimates you came up with during the process).
Looking at how much time you thought the task would take and comparing it to how long it really took is a fantastic way to see how accurate your estimates were. This useful data will help you estimate more effectively next time.