<b>The survival curve of a B2B lead: why conversion isn't a rate, it's a function of time</b>

<b>The survival curve of a B2B lead: why conversion isn't a rate, it's a function of time</b>

Reporting 'lead conversion rate' as a single number is a category error for long-cycle B2B. Conversion is not a fixed probability; it is a hazard function over time, and partner-sourced leads have a different curve than inbound.

<b>What survival analysis reveals:</b>

— <b>Front-loaded inbound.</b> Self-serve and high-intent inbound leads convert fast or not at all — a steep early hazard, then a long flat tail of non-converters.
— <b>Back-loaded partner/referral.</b> Partner-sourced enterprise leads often show low early conversion and a fatter mid-cycle hazard: they convert later, because the partner is shepherding a considered, multi-stakeholder purchase.

Measured at day 30, the inbound lead looks superior. Measured at day 180, the partner lead frequently catches up or surpasses it, and at higher ACV. Programs that cut partner spend on early-window data are reading the curve at the wrong x-coordinate.

<b>The methodological fix:</b> use Kaplan–Meier-style survival curves (or at minimum, cohort-by-month-aged conversion) per source, and compare sources at a maturity horizon matched to the sales cycle — not at an arbitrary, source-agnostic checkpoint.

<b>Implications:</b> never compare two lead sources at a single point in time unless their hazard shapes are known to be similar. They usually aren't, and the comparison favors fast-decaying inbound over slow-burning partner pipeline.

<b>Open questions:</b> how long a maturity horizon is honest, given that an unconverted lead at day 365 may still close — or may simply be dead?