FlowProofsGlossary
Bridge chart (waterfall chart)
A bridge chart, also called a waterfall chart, starts at one total, adds and subtracts a floating bar for each cause, and ends at the new total.
Green bars push the number up and red bars pull it down, each starting where the last one ended. The eye reads it left to right as a story: where we started, what happened, where we are.
It only works when the bars add up exactly to the difference between the two totals. A bridge with a mystery gap invites the one question nobody in the meeting can answer.
Worked example: from last month's profit to this month's
Profit was $58,000 last month and $63,000 this month. The higher price added $12,000, selling fewer units cost $5,000, and a lower unit cost added $3,000. Higher marketing spend took $5,000.
Four bars, $58,000 + 12,000 − 5,000 + 3,000 − 5,000 = $63,000. The bridge closes exactly, and the biggest bar tells you what to talk about first.
Try it in FlowProofs: see a live bridge in the demo
Related terms
- Variance analysis: Variance analysis compares an actual number with a reference (the budget, last month, last year) and splits the difference into the drivers that caused it.
- Price-volume-mix analysis: Price-volume-mix (PVM) analysis splits a change in revenue or margin into three effects: prices changed, more or fewer units sold, and the share of each product in what sold changed.
- Driver tree: A driver tree breaks one result, such as profit, into the inputs that produce it, joined by arithmetic, so you can see which input moved the result.