The Precision Effect
Use precise numbers and prices to signal knowledge and fair value
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 5
- Confidence
- 86%
Schindler's research shows precise numbers are judged more credible than round ones: an ad claiming a deodorant cuts perspiration by 47 or 53 percent was believed about 10 percent more than one claiming 50 percent, because we learn that vague round figures signal ignorance while precise ones signal knowledge. The effect extends to price. Janiszewski and Uy found people mentally discount round prices in larger jumps (500 down to 480, 460) but precise prices in smaller ones (505 to 502, 501), so precise prices feel more fairly set. Uber confirmed this at scale: customers accepted a 2.1x surge more readily than a 2x surge. The rule is to state claims, counts and prices precisely rather than rounding, since precision signals both knowledge and fair pricing.
Origin
From Schindler's precision-credibility study and Janiszewski and Uy's University of Florida pricing research, with real-world confirmation from Uber, as recounted by Richard Shotton.
Core principles
- 01Precise numbers are judged more credible than round ones
- 02People read precision as a signal of real knowledge
- 03Precise prices are assumed to be marked up more fairly
- 04Rounding down happens in smaller increments from precise prices
How to run it
- 1
Find your round figures
Locate the round numbers in your claims, stats, list counts and prices that read as vague estimates.
- 2
Make claims precise
State statistics and counts to the exact figure, since a precise number signals genuine knowledge and lifts believability.
Pro tip Dyson says 5,127 prototypes, not 5,000; call an article 11 reasons, not 10.
- 3
Price just off the round number
Where margins allow, set prices at a precise point rather than a round one so buyers assume a fairer markup.
Pro tip Precise prices are discounted mentally in smaller increments than round ones.
- 4
Keep it truthful
Only use precise figures that are actually accurate; invented precision is dishonest and erodes trust if exposed.
Watch out False precision can be misleading and legally risky.
- 5
Test against the round version
Compare credibility or conversion for the precise variant versus the round baseline to confirm the lift.
In the wild
Uber tested surge pricing at scale, offering some customers a 2x multiplier and others 2.1x. Customers were more likely to accept the precise 2.1x price than the round 2x, mirroring the lab finding that precise prices feel more fairly set. It confirmed Janiszewski and Uy's result in a far larger real-world sample.
→ The precise surge price won higher acceptance than the round one.
Schindler ran identical deodorant ads differing only in the perspiration-reduction figure. The precise claims of 47 or 53 percent were believed about 10 percent more than the round claim of 50 percent, because precision reads as knowledge while round numbers read as guesses.
→ Precise claims were roughly 10 percent more believable.
Common mistakes
Defaulting to round numbers
Round figures read as vague, plucked-from-the-air guesses, lowering both credibility and perceived pricing fairness versus precise ones.
Inventing false precision
Precise numbers only work when true; fabricated precision is dishonest and collapses trust if customers discover it.
Is it for you?
Best for
Marketers, copywriters and pricing teams making claims or setting prices.
Not ideal for
Contexts where false precision would be dishonest or legally risky.
From the transcript
“if someone says something in round, vague terms, they often don't know what they're talking about. Whereas if they talk precisely, it's from a position…”
“people who are more likely to accept the 2.1x price”
From the episode
8 Fascinating Psychological Biases - Richard Shotton - #592
Richard Shotton