The share of records that reached one stage and went on to reach the next.
Stage conversion is records reaching stage n+1 over records that reached stage n: lead to opportunity, discovery to proposal, proposal to won. A funnel has one per step, and their product equals the close rate, which is the check that the stage counts are consistent. It is the diagnostic rate: it shows where deals are lost, which win rate and close rate do not.
Records that reached stage n plus one divided by records that reached stage n.
Qualified to discovery 60 percent, discovery to proposal 73, proposal to won 50. The product, 22 percent, equals the close rate.
Stages that mean different things to different reps, so the rates describe data entry habits.