“70% confident” is one of my favorite concepts. I think it’s been kicking around for a while, but Jeff Bezos articulates it well (emphasis mine):

First, never use a one-size-fits-all decision-making process. Many decisions are reversible, two-way doors. Those decisions can use a light-weight process. For those, so what if you’re wrong? I wrote about this in more detail in last year’s letter.

Second, most decisions should probably be made with somewhere around 70% of the information you wish you had. If you wait for 90%, in most cases, you’re probably being slow. Plus, either way, you need to be good at quickly recognizing and correcting bad decisions. If you’re good at course correcting, being wrong may be less costly than you think, whereas being slow is going to be expensive for sure.

Third, use the phrase “disagree and commit.” This phrase will save a lot of time. If you have conviction on a particular direction even though there’s no consensus, it’s helpful to say, “Look, I know we disagree on this but will you gamble with me on it? Disagree and commit?” By the time you’re at this point, no one can know the answer for sure, and you’ll probably get a quick yes.

2016 Letter to Shareholders

I find the concept to be particularly helpful in software development. When shaping a project, my goal is to get to 70% confident on these criteria:

• The proposed solution squarely addresses the opportunity.
• We can complete the project within the stated appetite.
• We will be able to meet or exceed expectations of quality.

I use the concept actively, too. Here’s an example dialogue with a teammate:

Me: What’s your current level of confidence with the proposed project?

Teammate: Oh, maybe 50%.

Me: What additional information would get you to 70% confident?

Teammate: Well, I’m still uncertain about X and Y.

Me: Ok, let’s explore those further.

Applied to software development, “70% confident” is both subjective and objective:

• Subjective because humans ultimately evaluate the project against the criteria (e.g. “did this project meet or exceed our expectations of quality?” is squishy).
• Objective because you should hit the target seven times out of ten (three times out of ten is not 70%).

“70% confident” is a useful communication tool for finding the sweet spot between not enough planning and analysis paralysis.