Calculator Inputs
Example data table
| Campaign | Exposed Sample | Exposed Positive | Control Sample | Control Positive | Exposed Rate | Control Rate | Lift |
|---|---|---|---|---|---|---|---|
| Spring Awareness | 1,200 | 414 | 1,180 | 320 | 34.50% | 27.12% | 7.38 pts |
| Video Retargeting | 900 | 297 | 920 | 230 | 33.00% | 25.00% | 8.00 pts |
| Creator Partnership | 1,050 | 336 | 1,040 | 278 | 32.00% | 26.73% | 5.27 pts |
Formula used
1) Intent rate for each group
Exposed intent rate = Exposed positive responses ÷ Exposed sample size
Control intent rate = Control positive responses ÷ Control sample size
2) Absolute and relative lift
Absolute lift = Exposed rate − Control rate
Relative lift = (Absolute lift ÷ Control rate) × 100
3) Statistical significance test
The calculator uses a two-proportion z-test.
Z = (Exposed rate − Control rate) ÷ Pooled standard error
4) Confidence interval for lift
Lift CI = Absolute lift ± (Critical z × Unpooled standard error)
5) Forecasting outcomes
Incremental intent respondents = Absolute lift × Target population
Projected incremental buyers = Incremental intent respondents × Intent-to-purchase conversion rate
Incremental revenue = Projected incremental buyers × Average order value
ROI = ((Incremental revenue − Campaign cost) ÷ Campaign cost) × 100
How to use this calculator
Step 1
Enter the campaign name so exports and reports stay clearly labeled.
Step 2
Input exposed and control sample sizes along with the number of positive purchase-intent responses in each group.
Step 3
Choose a confidence level. Higher confidence is stricter and may reduce the chance of calling a lift significant.
Step 4
Add target population, conversion rate, order value, and campaign cost to turn survey lift into business outcomes.
Step 5
Click the calculate button. Results will appear above the form, including lift, significance, confidence interval, projected buyers, revenue, and ROI.
Step 6
Use the CSV or PDF buttons to export the result summary for presentations, client reports, or internal review.
Frequently asked questions
1) What does purchase intent lift measure?
It measures how much more likely exposed respondents are to report purchase intent compared with a comparable control group that did not see the campaign.
2) Why do I need both exposed and control groups?
A control group gives you a baseline. Without it, you cannot tell whether intent changed because of the campaign or because of existing brand demand.
3) What is the difference between absolute and relative lift?
Absolute lift is the percentage-point gap between exposed and control rates. Relative lift expresses that gap as a percentage of the control rate.
4) When is lift statistically significant?
Lift is statistically significant when the observed difference is large enough relative to sampling noise to pass the selected confidence threshold in the two-proportion z-test.
5) Why include an intent-to-purchase conversion rate?
Not every lifted survey response becomes an actual buyer. This rate helps convert survey movement into a more practical buyer forecast.
6) Can I use this for brand lift studies?
Yes. The same exposed-versus-control framework works for many survey-based outcomes, including awareness, favorability, message association, and purchase intent.
7) What if my control intent rate is zero?
Absolute lift, significance, and interval estimates still work. Relative lift becomes undefined because you cannot divide by a zero baseline.
8) Why might lift be positive but not significant?
A small sample, low response count, or noisy data can make an observed lift too uncertain. In that case, the point estimate is positive but not dependable yet.