Every satisfying tapstarted as a row ina spreadsheet.
Design data, delivered weekly. No fluff, no listicles.
Five insights you probably argued from intuition.
Each piece below is an excerpt from a past issue. The data was there. Most designers just didn’t have it in the room.
Tap Completion Rate by Response Latency
n = 2.4M interactions across 14 iOS/Android apps · Q4 2025
Tap completion rates collapse past 500ms — but the real cliff is at 1 second, where 91% of users abandon the interaction entirely. The 200ms window isn't a guideline; it's a revenue threshold.
“The difference between 200ms and 1s isn't annoyance. It's abandonment.”
'I trust this interface' — User Agreement
Survey, n = 840 participants · Three whitespace density conditions
Generous whitespace condition
Dense layout condition
In A/B tests across e-commerce checkout flows, generous whitespace treatment increased perceived trustworthiness scores by 23 points — more than adding a security badge. Whitespace isn't empty space. It's a signal.
Comprehension Score vs. Line Length
Eye-tracking study · 1,200 participants · Typeset Issue #24
Line length correlates inversely with comprehension past 80 characters — but the slope is gradual until it hits the 80-character threshold, where drop-off accelerates. Every character beyond 80 costs you a reader.
“80 characters isn't an opinion. It's where the data bends.”
Don’t read it in someone else’s summary.
Error Recovery Rate by Indicator Type
Usability audit · n = 320 · Includes 8% color vision deficiency sample
Red-only error states fail 8% of users with color vision deficiencies — but the fix isn't adding green. It's adding shape. Icon + color combinations reduce missed errors by 34% across all user groups.
Feature Recall Accuracy at 7 Days
Longitudinal study · n = 560 · Micro-interaction presence vs. absence
Users who experienced meaningful micro-interactions (progress confirmation, state change animation) recalled the feature 2.3× more accurately in a 7-day follow-up test. Micro-interactions aren't polish. They're memory formation.
“Delight is a mnemonic device, not a luxury.”
“I sent Issue #31 to my PM before our sprint retro. We shipped the latency fix the same week.”
“The whitespace data alone was worth three months of subscription. I use it in every client pitch.”
“Finally a newsletter that treats me like I can read a chart. No metaphors, no vibes — just data.”
The next issue covers scroll velocity and why your users stop reading before the fold.
Data from 8.3M scroll sessions, annotated for the design decisions hiding in the numbers.