What are Incremental Conversions?

• Incremental conversions measure the additional number of conversions caused by an intervention (treatment) compared to what would have happened without it (control).
• It’s the extra conversions directly attributable to the campaign, promotion, or treatment — not just the total conversions.

In short:

$\text{Incremental Conversions} = \text{Conversions (Treatment)} – \text{Conversions (Control)}$

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Formula

If we split users into treatment (received campaign) and control (no campaign):

$\text{Incremental Conversions} = \Bigg( \frac{y^T}{n^T} – \frac{y^C}{n^C} \Bigg) \times N$

Where:

• $y^T$ = number of conversions in treatment group
• $n^T$ = number of users in treatment group
• $y^C$ = number of conversions in control group
• $n^C$ = number of users in control group
• $N$ = total population (users you would target in reality)

This adjusts for baseline conversion rate and scales up to the full population.

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Example

Suppose you run a marketing campaign with 10,000 users:

• Treatment group: 5,000 users → 600 conversions (12%)
• Control group: 5,000 users → 400 conversions (8%)

Difference in conversion rate:

$12\% – 8\% = 4\%$

Incremental conversions (if all 10,000 users were targeted):

$0.04 \times 10{,}000 = 400$

Interpretation: The campaign generated 400 incremental conversions above what would have happened naturally.

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Why is this important?

• Total conversions can be misleading — some would have converted anyway.
• Incremental conversions isolate the causal effect of the treatment.
• This is the foundation of uplift modeling and incrementality testing in marketing, ads, and A/B testing.

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Use Cases

1. Digital marketing: Did the ad campaign actually drive more purchases, or would those users have purchased anyway?
2. Product experiments: Did a new feature lead to more sign-ups compared to not releasing it?
3. Healthcare: Did giving a treatment lead to additional recoveries versus natural recovery rate?

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Key takeaway:

• Conversions = everyone who converted, regardless of cause.
• Incremental conversions = the portion of conversions that only happened because of the intervention.