Dynamic Propensity Modeling: Bidding on Who’s Likely to Convert, Not Who Already Did

Most bidding optimizes on past conversions. Propensity modeling scores how likely each user is to convert next — letting you bid forward, toward future value, instead of backward.

June 27, 2026 · 6 min read · Richard C.
What we solve

Are you bidding on past conversions — or future likelihood?

$8,800

a month — about $105,600/yr — going to clicks that never convert.

Backward vs. forward bidding How propensity scoring works Why bidding forward wins Isn’t smart bidding already predictive? Backward vs. forward bidding How propensity scoring works Why bidding forward wins Isn’t smart bidding already predictive?
Quick answer

Dynamic propensity modeling scores each user or segment by their predicted likelihood to convert, so bidding can target future probability rather than only reacting to past conversions. It lets you bid forward — paying more for high-propensity prospects before they convert — instead of optimizing purely on conversions that already happened, which improves efficiency and reach into new demand.

TL;DR
  • Standard bidding optimizes on conversions that already happened.
  • Propensity modeling predicts who is likely to convert next.
  • It scores users or segments by conversion probability.
  • You bid forward toward future value, not backward at history.
  • It reaches high-likelihood prospects before they convert.

Most bidding is fundamentally backward-looking. Smart bidding learns from conversions that already happened and chases more users who look like past converters. That works, but it’s reactive — you’re always optimizing toward the rear-view mirror. Dynamic propensity modeling flips the orientation: instead of asking “who looks like people who converted,” it asks “who is likely to convert next,” scoring each user or segment by predicted probability so you can bid forward, toward future value.

The shift from reacting to past conversions to predicting future ones is subtle but powerful — it lets you pay the right amount for a prospect before they’ve proven themselves, and reach demand that pure look-back bidding misses.

Backward vs. forward bidding

The orientation of the signal changes everything about what you can target and when.

Reactive vs. predictive bidding
Past-conversionPropensity
Optimizes onWhat happenedWhat’s likely
OrientationBackwardForward
TargetsLook-alikes of convertersHigh-probability prospects
Reaches new demandLimitedBetter

How propensity scoring works

A propensity model uses behavioural and contextual signals — engagement, recency, attributes, journey stage — to estimate each user’s probability of converting. Those scores become an input to bidding: bid up for high-propensity users, down for low. Crucially the scores are dynamic, updating as behaviour changes, so a prospect warming up gets bid up before they convert, not after.

Signals that feed a propensity score
Recent engagement84score
Journey-stage signals78score
Fit / attributes70score
Past-conversion similarity60score

Relative predictive weight.

Source: Illustrative — directional

Why bidding forward wins

Reactive bidding can only chase patterns it has already seen, so it’s slow to value a new kind of high-intent prospect and tends to crowd the same proven pockets. Predicting propensity lets you value a prospect on their trajectory, not just their resemblance to history — bidding appropriately for someone clearly heading toward a purchase even if they don’t yet match the look-alike profile. That foresight captures demand before competitors’ look-back models react.

Forward
bid on likelihood, not just history
Dynamic
scores update as behaviour changes
Earlier
value prospects before they convert
Source: Directional — predictive practice

Isn’t smart bidding already predictive?

Optimizing only on past conversions is driving by the rear-view mirror. Dynamic propensity modeling lets you look through the windshield — scoring who’s likely to convert next and bidding toward that future value. It’s how you reach high-intent demand before it shows up in yesterday’s conversion data.

3,100
“Marketing Analyst” searches / mo (U.S.)
+0%
specialist demand vs 2 yrs ago
$72k
U.S. avg. salary — what this expertise costs to hire
Source: Ahrefs search demand + U.S. salary averages · roles: Marketing Analyst, Data Scientist
RC
Article by

Richard Castello

Richard leads performance and search strategy at PPC Snobs. He’s spent over a decade architecting paid acquisition engines for DTC and B2B brands — managing live budgets at scale, not recycled SEO filler or AI-only takes.

FAQ

Questions, answered.

It scores each user or segment by their predicted likelihood to convert, using behavioural and contextual signals, and updates those scores as behaviour changes. Bidding then targets future probability rather than only reacting to past conversions.

From the author

Why this matters.

Richard Castello on the thinking behind it.

RC
Richard Castello
CEO & Founder

Smart bidding isn’t dumb — it’s obedient. It scales exactly what you tell it is valuable, so defining “valuable” is the whole game.

RC
Richard Castello
CEO & Founder · PPC Snobs

Feed the algorithm clean, profit-weighted signals and it finds margin you’d never spot by hand. Feed it junk and it scales the junk.

RC
Richard Castello
CEO & Founder · PPC Snobs

Performance Max isn’t out of control. It’s doing precisely what your structure and your feed told it to do.

RC
Richard Castello
CEO & Founder · PPC Snobs
Pricing

Investment scales with ambition.

Two ways to engage. Both transparent — no SDR follow-ups, no proposal theatre.

Self-serve

Build your own retainer

Pick the modules you need. See exact one-time and monthly investment before you commit to anything.

Live total calculator
Modular pricing — no bundles
AI-enable, then scale on agents
Open the configurator →
RecommendedWhite-glove

Request a custom quote

For complex stacks, multi-brand portfolios, or projects above $50K/mo. Scoped on a call, priced on a doc.

Architecture audit included
Quarterly business review
Dedicated account manager