GIFSQ Tools · Module 12 — Sensory · Tool 239 of 500
Size a consumer survey: how many invitations to send for a target number of replies at an expected response rate, and the estimated completion time.
Try sample values — fills the form with the worked example below.
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Invitations to send
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Estimated time (min)
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Target replies
Equation: Invitations = ⌈target ÷ (rate ÷ 100)⌉; estimated minutes = questions × minutes per question.
Method: ISO 11136:2014 consumer testing practice; survey sizing from the target sample and the expected response rate.
Assumptions: The response rate is the share of invitees who complete the survey; completion time is the same for every respondent.
Limitations: The rate is an estimate — send invitations in waves and top up if replies fall short.
Rounding: Invitations are whole numbers (rounded up); minutes to 2 decimal places.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: ISO 11136:2014 consumer testing practice; survey sizing from the target sample and the expected response rate.
Assumptions: The response rate is the share of invitees who complete the survey; completion time is the same for every respondent.
Limitations: The rate is an estimate — send invitations in waves and top up if replies fall short.
Rounding: Invitations are whole numbers (rounded up); minutes to 2 decimal places.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: 10 questions, 200 target replies, 25% response rate, 0.5 minutes per question: 800 invitations, 5.00 minutes estimated.
Enter values above to see results.
Tool 239 of 500 — GIFSQ
