Case Study · Growth Analytics

Paid Media
Incrementality
Analysis

A causal analysis showing why platform-reported performance overstated true paid media impact, and how budget could move toward audiences with stronger incremental lift.

Focus
Incrementality · Paid media · Budget allocation
Stack
Python · SQL · Propensity score matching · Causal inference
Type
Portfolio case study
Audience incrementality · before reallocation
RetargetingProspectingLAL 1%TikTokLAL 3–5%−80%+lift
Audience incrementality · before reallocation
3.0x
Reported ROAS
1.25x
Incremental ROAS
CPA: reported → incremental
Meta Retargeting Hot€55 €500
YouTube Retargeting€75 €833
TikTok Broad 18–24€85 €137
3.0x1.25x
ROAS corrected
€106€246
CPA adjusted for incrementality
6142526400
Reported vs incremental conversions
+8400
Incremental conversions after reallocation
The problem

The dashboard rewarded
proximity, not causality.

Dashboards showed 3.0x ROAS and €106 CPA. Incrementality analysis showed 1.25x ROAS and €246 true incremental CPA. The gap came from attributed conversions that would likely have happened anyway, especially in retargeting audiences.

What looked wrong
ReportingPlatform attribution credited conversions that were not fully incremental
MarketingRetargeting looked efficient because it reached high-intent users
GrowthProspecting looked weaker because it reached colder users
DecisionBudget needed to follow incremental lift, not reported CPA
Findings
What changed the read.
01

Reported CPA understated the real cost

Reported CPA was €106, while true incremental CPA was €246.

02

57% of attributed conversions were not incremental

Paid media reported 61425 monthly conversions, but only 26400 were incremental.

03

Retargeting was overvalued

Meta Retargeting Hot looked best at €55 reported CPA, but rose to €500 incremental CPA after adjustment.

04

Prospecting was undervalued

TikTok Broad and Meta lookalike audiences produced stronger incremental lift than retargeting.

05

Frequency waste started after 9 impressions

Incremental conversion peaked at 6–9 impressions, then declined as frequency increased.

06

Reallocation added growth without more budget

Moving spend from retargeting to prospecting added +8400 incremental conversions per month.

Method
Measuring lift beyond platform reporting.

Four layers, applied in sequence.

I

Cohort definition

Defined exposed and comparison users across paid media audiences, markets, channels, and observation windows.

II

Propensity score matching

Matched exposed users with comparable unexposed users using pre-campaign behavior, country, device, loyalty, and organic activity.

III

Incrementality by audience

Compared reported conversions, incremental conversions, reported CPA, true incremental CPA, and lift rate by audience.

IV

Reallocation simulation

Modeled how moving budget from low-incrementality retargeting to higher-incrementality prospecting would change results.

Evidence

What the causal
read showed.

Propensity score matching
Before matching
After matching

Matching aligned treated and control groups on pre-campaign behavior before measuring lift.

Reported CPA vs incremental CPA
Meta Retargeting Hot€55 €500
YouTube Retargeting€75 €833
TikTok Broad 18–24€85 €137

Cheapest reported CPA audiences were often the most expensive on an incremental basis.

Frequency and incremental CVR
4.9% peakwaste zone1–23–56–910–1415–2021+

Incremental CVR peaked at 6–9 impressions. Beyond 9, each additional impression yielded declining return.

Budget reallocation impact
Current baseline
26400
Retargeting cuts
−4200
Prospecting scale
+12600
Optimised total
34800
Net gain: +8400 incremental conversions€0 extra budget
Decision

Move budget toward
true lift.

Retargeting was taking too much credit for conversions likely to happen anyway. Budget should move toward TikTok and Meta prospecting, where the ad had more room to change behavior.

TikTok Broad 18–24
Scale
Meta LAL 1%
Scale
Meta LAL 3–5%
Scale
TikTok Broad 25–34
Scale
TikTok Retargeting
Cut
Meta Retargeting Warm
Cut
Meta Retargeting Hot
Cut
YouTube Retargeting
Cut
Business impact

More incremental growth,
no budget increase.

The recommendation kept spend flat while moving budget toward audiences with stronger causal impact and away from retargeting segments that looked efficient only in platform reporting.

Budget shifted€1.3M from retargeting to prospecting
Incremental conversions+8400 per month
True CPA€246 → €187
Annual incremental revenue+€30.2M
Budget increase€0
Recommendations

Use incrementality as
the media decision layer.

1

Replace reported CPA with incremental CPA

Use reported metrics for monitoring, but use incremental CPA for budget decisions.

2

Move €1.3M from retargeting to prospecting

Shift budget toward TikTok Broad and Meta lookalike audiences with stronger lift.

3

Cap retargeting frequency at 9 impressions

Reduce waste once incremental conversion starts to decline.

4

Use UGC as the default for prospecting

UGC outperformed branded studio content by 17 percentage points on incremental lift.

5

Review market allocation

Germany was underinvested in prospecting despite having the lowest brand awareness across the three markets.

My role

What I owned.

I structured the incrementality analysis, prepared exposed and comparison cohorts, applied propensity score matching, compared reported and incremental performance, analyzed audience-level efficiency, modeled reallocation scenarios, and translated the findings into media budget recommendations.

What this shows
Measure paid media performance with causal thinking, not only platform reporting.
Separate attributed conversions from true incremental impact.
Turn audience-level analysis into budget allocation recommendations.
Next.

Explore the rest of the work.

The repository includes cohort definitions, propensity score matching, audience-level incrementality comparison, frequency analysis, and reallocation modeling.

Maïssa Bounar© 2026

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