
YC's Approach to User Interviews — Drop "Would You Use This?" and Ask About the Past
No market need is the top startup killer at 42%. Here is how Y Combinator teaches founders to design interview questions and validate differently at each stage.

Early-stage startups with weak traction persuade investors not by excusing absent revenue but by evidencing the growth that is coming. Pre-revenue signals — engagement, retention, pilots, LOIs, waitlists — fill the traction gap, while market insight, team, and founder-market fit complete the belief that this team will produce that growth.
The nature of early investment, particularly pre-seed and seed, is betting on an unvalidated future rather than finished numbers. If revenue were already large, the round would not be early by definition.
No. Early investors bet on evidence of growth potential rather than completed results, and what you fill the traction gap with is what decides the round.
There is a paradoxical data point. DocSend's March 2026 pitch deck analysis found investors view a seed deck for an average of 3 minutes 44 seconds, with only 58% reaching the final slide.
Yet the same analysis found investors spent 80% longer on the traction slide of companies that failed to raise.
Dwelling on weak traction is not admiration. It is the signal of someone looking for a reason to decline.
So the strategy is clear: rather than inflating traction that does not exist, redirect investor attention toward stronger signals.
The same DocSend data showed where investors actually spent their time:
| Slide | Time spent |
|---|---|
| Business model | 64 seconds |
| Product | 59 seconds |
| Traction | 40 seconds |
| Team | 38 seconds |
The centre of gravity in early persuasion is not a revenue figure. It is the story of why this product works and how it makes money.
When revenue is thin, show the signals that immediately precede revenue — leading indicators. While lagging metrics like revenue and MRR remain slim, retention, engagement and PMF surveys prove with data that the growth is a matter of time.
The most widely used benchmark. Devised by Sean Ellis, who drove Dropbox's growth in 2010, it asks "How would you feel if you could no longer use this product?" A "very disappointed" rate above 40% is treated as a product-market fit signal.
Email client Superhuman is frequently cited for using this survey systematically to push its PMF score above 40%.
Lenny Rachitsky's six-month user retention benchmarks:
Rachitsky says "great retention is the best indicator of product-market fit." Which is why a single retention curve that flattens rather than decaying to zero can substitute for traction even when the revenue graph is thin.
Even at zero revenue, willingness to pay can be documented. B2B makes demand visible through POCs, pilots and LOIs; B2C through waitlists and invite conversion rates.
Alchemist Accelerator distinguishes the three stages clearly:
But Alchemist is emphatic that an LOI is fundamentally a non-binding stepping stone, not a guarantee of future revenue. So investors look past the LOI count to whether the customer actually committed something — time or money.
The point is climbing it:
Expressed interest < signed LOI < paid pilot < renewed contract
One paid pilot outweighs ten unsigned LOIs.
Waitlists work the same way. The real demand signal is not the headline number but what percentage of invited users actually activated.
The thinner the leading indicators, the more the persuasion shifts to market insight, timing and team.
NfX general partner James Currier says "investors buy your future, not your past." He frames "Why Now" as the element that substitutes for historical traction data, advising founders to prove what recently changed that suddenly made this opportunity executable.
Notably, DocSend's pre-seed report found only 53% of successful decks included a "why now" slide — which reads as evidence that timing narrative remains an underrated differentiator.
Team, and specifically founder-market fit, is the strongest available evidence when traction is absent. First Round Review partner Bill Trenchard advises finding "a very original path to convince people that you might be right and everyone else wrong."
He simultaneously stresses disclosing what you have not yet solved first, arguing that honesty builds credibility.
For reference, DocSend's pre-seed report found teams with three co-founders raised the most, averaging $511,522.
Weak traction is not a defect in an early-stage startup. It is closer to the definition of "early." The problem is not the absence itself but what fills it.
As the DocSend data shows, the longer an investor studies weak traction, the closer they move to declining. So move their attention elsewhere.
For the lived experience of the fundraising grind, see 50 Investor Pitches, Zero Funding: What One Founder Learned. For what happens once interest turns into terms, see Why the Term Sheet Stage Decides Your Startup's US Venture Deal.
DocSend's March 2026 analysis found an average of 3 minutes 44 seconds for a seed deck, with only 58% reaching the last slide. By slide: business model 64 seconds, product 59, traction 40, team 38.
No. DocSend found investors spent 80% longer on the traction slide of companies that failed to raise. Extended attention on weak traction resembles someone searching for a reason to decline.
Sean Ellis’s survey asks how users would feel if they could no longer use the product. A "very disappointed" response rate above 40% is treated as a product-market fit signal.
Alchemist Accelerator states an LOI is a non-binding stepping stone, not a guarantee of revenue. The evidence ladder runs from expressed interest to signed LOI to paid pilot to renewed contract — one paid pilot beats ten unsigned LOIs.
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No market need is the top startup killer at 42%. Here is how Y Combinator teaches founders to design interview questions and validate differently at each stage.

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