Reach & Frequency
Part of Media audience research
Comparing audience sources with different definitions
Compare Census, media-use and ad-planning figures by population, period, geography, denominator and method before using them in a media decision.
When audience figures disagree, compare what each one counts before comparing the values. A resident count, a media-use survey and an ad-plan forecast can all be valid while answering different questions.
Capture the definitions
Record each figure's unit, population, geography, age range, period and method. Note whether it measures content use or advertising inventory.
| Question | Definition to capture |
|---|---|
| Who is counted? | Residents, surveyed adults, internet users, accounts or people forecast to see an ad |
| Where and when? | Geographic boundary, reporting period and forecast dates |
| What activity qualifies? | Any use, use within a recall period, a visit or planned ad exposure |
| What is the denominator? | All residents, an eligible age group, online users or a supplier-defined audience |
| How was it produced? | Census count, weighted survey, measured audience or modelled forecast |
Do this before converting counts to percentages. Two figures labelled “reach” may have different denominators.
Check source-specific differences
In the ABS's 2021 Census QuickStats, person figures use place of usual residence, not where a person was counted on Census Night. They describe residents of a selected area at that Census; they do not establish current media use.
Ipsos iris measures Australian digital content audiences. Its reported audience universe changed from age 14 and over to age 18 and over from the July 2026 reporting period, and Ipsos says comparisons across that break are invalid.
Check the reporting period and covered devices before using an iris figure. Neither a media-use result nor a digital content audience automatically represents bookable ad inventory.
For an ad-planning forecast, record the plan settings and how the supplier defines and reports its audience. Do not treat a forecast as equivalent to a resident count or media-use measure unless the definitions align.
Key Changes in Ipsos Iris Digital Audience Measurement (July 2026)
- Audience Age Range Change
- 14+ → 18+
- Impact on Comparability
- Comparisons across the change are invalid
- Reporting Period & Devices
- Check before use; not automatically bookable inventory
Decide whether comparison is possible
Imagine a local service business with an ABS resident count, a national media-use percentage and a supplier forecast. Use the count to understand the geographic base, the survey to investigate whether the medium is relevant, and the forecast to assess the proposed buy under its settings.
Do not average the three figures. This is an illustrative workflow, not a calculation for a real market.
For a direct comparison, check whether both sources can use the same geography, age range, dates, devices and activity definition. Record differences that remain, including sampling and modelling. If alignment needs unsupported assumptions, show the figures separately with their definitions.
Name the source fit for the decision, what it cannot establish and what evidence is needed next.
Using ABS Census vs Media-Use Surveys vs Ad-Planning Forecasts
- Pros of ABS Resident CountRepresents actual population base; reliable for geographic planning; based on official census data
- Cons of ABS Resident CountDoes not reflect current media use; based on usual residence, not location on Census Night
- Pros of Media-Use Survey (e.g., ACMA Annual Consumer Survey)Measures real media engagement; includes device and platform detail; high methodological transparency
- Cons of Media-Use SurveyMay not align with ad inventory; sampling limitations; not always suitable for planning buys
- Pros of Ad-Planning ForecastTailored to campaign settings; useful for estimating reach under specific targeting rules
- Cons of Ad-Planning ForecastModelled, not observed; depends on supplier definitions; may not match resident or usage counts
