Lesson 2 of 2 in this stage
Testing longevity: a fair comparison between two perfumes
Design a comparison with consistent conditions and a defined longevity endpoint.
Define the endpoint
Choose an endpoint such as 'I can no longer distinguish it nearby after a break'. Do not use different criteria for the two perfumes. Record a result for your conditions, not guaranteed hours for everyone. If checking every two hours, you cannot claim the disappearance minute; the endpoint falls between checks.
Amount and surface change the comparison
Three large sprays on fabric versus one small spray on skin do not isolate the formulas. Match surface, spray count and application as far as practical, noting that atomizers may deliver different amounts per spray. Use fabric only if product directions allow and after checking a hidden area; staining can occur.
Repeating reveals consistency
Repeat on another comparable day and swap the order. If results vary, report a range rather than selecting the longest observation. Washing, rubbing or changing clothes may remove scent, while adaptation changes perception. A home trial cannot isolate everything, but becomes useful when its limits are stated.
A fair longevity comparison between A and B
If A receives three sprays on fabric and B one spray on skin, their longevity results are not directly comparable. Dose and substrate both changed. Compare on similar blotters or in reasonably matched skin sessions and record the final interval when a clear scent is still detectable.
Repeat and reduce bias
A single session does not establish a general rule. Repeat the comparison and vary the order to reduce expectation and adaptation effects. Report the variation between trials. If results vary widely, say so rather than claiming one exact wear-time number for everyone.
Your turn
Use what you learned
A is one spray on skin; B is three on fabric. What must change before ranking longevity?
See the answer and why
Match surface, amount, conditions and endpoint. Otherwise we compare different use experiences rather than the formulas alone.
Check your understanding
Answer four questions, then review the reason for each answer. You can retry.
Practical sensory workshop
Compare equal sprays on equivalent strips at matching intervals. Repeat on another day and use a second evaluator because olfactory adaptation can mimic weaker persistence.
SESH exercise: choose two scents and record results before viewing their marketing descriptions.
