A test mailing can tell you something useful about an offer, but it cannot guarantee the result of the next campaign. Doubling the number of recipients does not automatically double the responses or the return.
The size of the test matters. A result based on a small sample leaves more uncertainty than a comparable result from a larger sample. That is why it is useful to consider a range of possible outcomes rather than one expected response rate.
What a probability range is trying to show
The original helpsheet presented a chart connecting the number of test recipients, the observed response rate and a range for a later mailing. Its purpose was to show how uncertain a test result can be.
The recovered chart has duplicated headings and inconsistent entries, so its numerical ranges have not been reproduced. They should not be treated as a reliable forecasting table.
Keep the comparison meaningful
A useful comparison assumes an identical mailing to the wider list. If the offer, audience or other conditions change, the first test is no longer the same comparison.
Before using a test result to plan a larger activity, set out:
- How many people received the test.
- What response the test produced.
- How closely the planned mailing matches the test.
- The uncertainty that remains around the eventual result.
A bigger test can give you more information, but it cannot remove every uncertainty about future customer behaviour.
Connect the result to the decision
Use the evidence to decide whether further testing is needed and whether the proposed spend is reasonable. Avoid presenting a single response figure as a promise.
If you need a numerical probability assessment, have the test data and method reviewed before relying on it. We can help organise the measurement of your marketing activity and discuss what the figures can reasonably support.