Ranged estimates compare logged progress against the initial forecast, making estimates better than ever before.
Why ranged estimates are more effective than single point estimates
In project management, the only thing you can be sure of is uncertainty. And change. This is why making ranged estimates for your projects is more realistic and reliable than aiming for a singular deadline.
Why?
Let’s start with a real-world example
We use ranged estimates all the time in daily life. For example, if someone asks you how long it takes to drive to work, you’ll probably say “between 20 and 35 minutes,” not “23 minutes.” Traffic, like projects, has a lot of variables.
If you’re leaving your house to go to a friend’s for dinner and you say, “I’ll be there in 25 minutes,” the chances of you arriving at that exact time are slim. Consequently, we build in mental buffers, because experience has taught us that someone arriving at the exact time they predict is unreliable. But the range, we can count on this. And so it goes for projects.
“When we first came up with this concept we were worried that folks wouldn’t get it,” says Tempo CTO and co-founder Jason Carlson. But it became quickly apparent how much easier it was for people to imagine the absolute best and worst case scenario for an item of work; especially if you compared this to committing to a single-point end date.
Ranged vs single-point estimates
Let’s compare the two with these scenarios:
Single-point deadline:
Let’s say you’re a developer working on a task in a team that uses single-point estimates. You’ve given an estimate of 10 hours for a work item. Still, a stakeholder or manager asks you (forcefully, pleadingly, convincingly) if you can shave that down to seven hours. There are many reasons to buckle and say Yes—you want to get the product out the door; you want to make your manager happy; you fear for your job—but you know it’s totally unrealistic unless you work 24 hours a day or compromise on the integrity of your work.
Ranged estimation finish dates:
Now, if you were using ranged estimates, and you identified best/worst case scenarios between eight and 12 hours, it changes the conversation. Instead of “why can’t you do it in less,” the dialogue shifts to talking about the two range dates and the cases around which makes them the best and worst cases.
Being able to have conversations with stakeholders, managers, and customers around these dates is empowering. It gives context to delivery times and improves understanding among everyone involved in the project.
Plus, estimating in ranges proves to be a great teacher for anyone estimating work. The more you do it, the better you get—just like anything else!
Using ranged estimates is not only the most realistic way of building a schedule, but it’s also one of the most effective ways to build confidence, create trust, improve relationships and create a winning reputation in your industry.
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