Calculate conversion, effort and cost
Course overview · 4 min reading + 12 min practice, estimated
Principles and method
A conversion rate is a numerator divided by an eligible denominator. State both counts, especially when samples are small. Cost should include relevant labour and channel expense, with allocation assumptions explained. Time-to-event measures need a start, end and handling rule for unfinished cases. Avoid ranking channels solely by cheap initial leads if downstream quality differs. Use medians or distributions where outliers distort averages. A numerical comparison is only useful when roles, seniority, geography and time windows are sufficiently comparable or their differences are acknowledged.
Worked example
Channel A produces 8 interested replies from 40 contacts, or 20%. B produces 3 from 10, or 30%. B’s higher observed rate is based on a much smaller sample and does not establish a durable advantage.
Put it into practice
Calculate interest rates and cost per interested conversation for two fictional channels, including recruiter time.
Use fictional information and keep your work in your own notes.
Compare your approach: self-review guidance
Show counts, formulae and assumptions. If a channel has no interested conversations, report the cost and zero outcome rather than inventing a finite cost-per-outcome value. Explain sample uncertainty.
Sources and further reading
Original Academy teaching and fictional examples. These references provide context, not endorsement. Edition 2026.09; updated 2026-09-24.
- CIPD: Recruitment
Professional context for the recruitment lifecycle.
- ICO: Recruitment and selection
UK guidance. Check its current status and updates before implementation.