Brand lift studies are an important tool for understanding the impact of advertising campaigns on brand metrics like awareness, consideration, and favorability. However, these studies require a certain level of media spend to generate a statistically significant sample size. In this article, we will explore the factors that determine the minimum spend for a brand lift study and provide general guidance on budgeting.
What is a brand lift study?
A brand lift study measures how exposed and unexposed groups respond differently to brand-related metrics before and after an advertising campaign. Participants are split into two groups: exposed to the campaign, and not exposed. By comparing changes in brand metrics between these groups, the incremental “lift” generated by the campaign is quantified.
Common brand lift metrics include:
- Brand awareness – % who are familiar with the brand
- Brand consideration – % who would consider purchasing
- Brand favorability – % who have a positive opinion of the brand
- Brand purchase intent – % who say they will purchase the brand
Brand lift studies require pre-campaign and post-campaign surveys to measure these metrics. Statistical modeling isolates the true impact of the campaign, removing effects of external factors.
Why determine minimum spend?
Spend levels for media campaigns typically need to generate a target number of impressions. Brand lift studies have minimum impression thresholds to produce statistically valid results at a desired confidence level.
Factors determining minimum spend include:
- Audience size
- Survey response rates
- Completion rate of those responding
- Desired statistical confidence level
With larger audience sizes, higher response rates, and higher completion rates, the minimum spend will be lower. Also, higher confidence levels require more responses, increasing minimum spend.
How big does the exposed sample need to be?
Sample size needed depends on desired confidence level. Common confidence levels are 90%, 95%, or 99%. Higher confidence levels require larger samples.
| Confidence Level | Sample Size Needed |
|---|---|
| 90% | 270 |
| 95% | 385 |
| 99% | 660 |
For example, for 95% confidence, 385 people exposed to ads would need to complete both pre- and post-campaign surveys.
Factors influencing exposed sample size
To achieve desired completed sample, must account for:
- Audience Reach – Total number exposed to campaign. Wider reach requires lower % of audience to complete surveys.
- Survey Response Rate – % agreeing to take survey. Higher response rates need fewer impressions.
- Survey Completion Rate – Of those responding, % finishing entire survey. Higher completion increases sample.
Balancing these factors allows estimating minimum impressions needed.
How to calculate minimum campaign spend
With minimum completed sample size determined, can estimate minimum spend by:
- Project number of impressions needed to reach sample based on reach and response/completion rates.
- Estimate cost per thousand impressions (CPM) for media channel(s).
- Multiply impressions by CPM to get minimum spend.
For example:
- Need 385 completed surveys for 95% confidence
- Audience reach of 1,000,000
- 2% survey response rate
- 60% completion rate
- CPM of $10
Calculations:
- Impressions needed = Completed Surveys / (Reach * Response Rate * Completion Rate)
- = 385 / (1,000,000 * 0.02 * 0.6) = 321,429 impressions
- Minimum spend = Impressions * CPM / 1000
- = 321,429 * $10 / 1000 = $3,214 minimum spend
Typical minimum spend benchmarks
As a general guideline, typical minimum spends for brand lift studies are:
| Media Platform | Minimum Spend |
|---|---|
| Facebook/Instagram | $5,000 – $10,000 |
| YouTube | $15,000 – $25,000 |
| Connected TV | $25,000 – $50,000 |
| Pandora Audio | $15,000 – $30,000 |
However, minimums vary based on audience size, reach, and other factors outlined above.
Best practices for minimum brand lift spend
To optimize brand lift studies, experts recommend:
- Set minimum spend levels during planning, based on reach and response rates.
- Use early campaign data to refine minimum spend estimates.
- Test at multiple spend levels and campaign lengths to optimize.
- Balance stat significance with budget limitations.
- Discuss tradeoffs of confidence levels with stakeholders.
Proper planning and execution is key to generating valid insights that influence marketing strategy.
Conclusion
Determining the minimum spend for a brand lift study depends on campaign reach, response rates, completion rates, and desired confidence level. While general benchmarks exist, minimum spends can vary widely based on audience size and campaign details. Best practices include setting minimum targets upfront, optimizing based on early results, testing multiple spend levels, and balancing statistical significance with budget realities through discussions with stakeholders.