DTC Reach and Frequency When the Addressable Audience Is Uncertain
A range-based way to plan DTC pharma reach and frequency when the true size of the addressable audience is unknown, with a sensitivity table.
The short answer
DTC pharma reach plans often start with a single audience number: "3.2 million adults with the condition." That number usually comes from prevalence estimates, a survey, or a partner's segment count. Each source has error. When the denominator is uncertain, reach percentages and frequency targets are uncertain too. Planning with ranges gives a more honest picture and helps avoid overspending on frequency.
Why the audience number is uncertain
- Prevalence estimates describe the population, not the part you can reach in a given partner's system.
- Segment counts reflect a partner's identity graph, which includes devices and households, not unique people.
- Survey-based sizes have sampling error and depend on how the condition is defined.
- Modeled segments include people who do not have the condition and miss people who do.
Plan with three audience sizes
Instead of one number, plan against a low, middle, and high estimate. Keep impressions fixed and see what happens to reach and frequency.
| Addressable audience | Impressions | Reach at plan | Average frequency |
|---|---|---|---|
| Low: 1.5 million | 20 million | 70% | 19 |
| Middle: 2.5 million | 20 million | 55% | 15 |
| High: 4.0 million | 20 million | 40% | 12 |
All figures are illustrative, and real reach curves depend on partner and channel.
If the true audience is small, the plan is heavy on frequency and may waste money on repetition. If it is large, reach is lower than hoped. The table makes both risks visible before launch.
Decide what you will do in each case
Write a rule for each scenario:
- If delivery shows frequency climbing above the cap early: the audience is likely at the low end. Shift budget to new partners or broaden contextual reach.
- If reach grows slowly and frequency stays low: the audience is larger or harder to reach. Consider adding channels.
This connects to scenario planning at the budget level.
Measure reach with honest definitions
Reach in DTC is usually reported as households or devices, not people. The MRC standards help define measured versus modeled reach. When combining channels, reach is not additive. See deduplicated reach across CTV and online video.
Frequency distribution matters more than the average
An average frequency of 12 can mean most people saw the ad 3 times and a small group saw it 60 times. Ask partners for the distribution. Set caps and monitor the share of impressions going to people above the cap.
Practical takeaway
Replace the single audience number in your plan with a low, middle, and high estimate and a table showing reach and frequency for each. Add a rule for what you will change if early delivery suggests you are at either end.
Sources
External guidance and platform documentation change. Links were current at publication; check them again before relying on them for a decision.
Editorial note. Analysis and frameworks are the author's own and do not represent Acxiom or any current or former employer, client, or named platform. Examples labeled hypothetical or illustrative are not results from real campaigns. Nothing here is legal, regulatory, or medical advice.
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I work on health and pharma data, identity, and activation, after five years running HCP and DTC programmatic agency-side. Happy to talk through how this applies to your situation.