Did it double, or go from 3 to 6? Relative vs. absolute change
Put each relative change next to the same change in units, and decide how big it really is.
Free course. Your Maestro, an AI, .
At La Ceiba's results meeting, the Ceiba Express manager presents her year: sales +133%. The room applauds. Then the Centro manager speaks: sales +6.3%. Nobody applauds.
Management wants to know which branch did the most for the chain's growth. Before you read on, make your call.
Check yourself: In 2025, which branch added more pesos to the chain's growth: Ceiba Express, which grew 133%, or Centro, which grew 6.3%?
Two sizes of the same change
Every change has two sizes, and both are true:
- The absolute change is the subtraction, in the units of what you measure: pesos, customers, complaints. Ceiba Express: 2.1 − 0.9 = 1.2 million pesos. Centro: 43.8 − 41.2 = 2.6 million.
- The relative change is that subtraction divided by the earlier value, the percentage from the previous page. Ceiba Express: 1.2 ÷ 0.9 = 133%. Centro: 2.6 ÷ 41.2 = 6.3%.
The relative change answers "how much did this branch change?" For Ceiba Express, which opened at the end of 2024, more than doubling its sales is great news. The absolute change answers "how much did the world change?" For the chain, Centro brought in more than twice as much new money.
The chain grew 6.55 million in total. Centro put in 2.6 million of that; Ceiba Express, 1.2. If you look only at percentages, you congratulate the wrong branch for the wrong reason. If you look only at pesos, you never see that a new store is taking off.
In the chart, each point is a branch (synthetic course data): across, its relative change; up, its change in pesos.
Step 1 of 4
The 24 branches
Each point is a branch. The further right, the more it grew in percent; the higher up, the more it grew in pesos. Before you go on, find which one is furthest right and which one is highest.
"Doubled," "tripled" and the 300% that doesn't exist
The language of relative change has a trap of its own. "Doubled" means growing 100%: what you had plus the same again. "Tripled" means growing 200%, not 300%: what you had plus twice that. Try it with a complaints case from the stores:
In 2024 there were 3 complaints about double charges at La Ceiba's registers; in 2025, 9. The chain issues about 40,000 receipts a year (invented numbers).
In 2024 there were 3 complaints about double charges at La Ceiba's registers; in 2025, 9. The chain issues about 40,000 receipts a year (invented numbers).
How many times as many, and what percent increase?
Example 1 of 2
antes = 3 # quejas en 2024
ahora = 9 # quejas en 2025
print(ahora / antes)
print((ahora - antes) / antes * 100)
A guess is fine: it's kept as you wrote it, so you can compare. Only you and your Maestro see your predictions.
Example 2 of 2, opens once you explain this one
If it still sounds odd that tripling is a 200% rise and not 300%, ask your Maestro.
You see this all the time in health and safety headlines: "such-and-such doubles the risk of such-and-such." It can be true and still mean the risk goes from 1 in 10,000 to 2 in 10,000. Before you get alarmed, or alarm others, ask from what to what.
The rule for your reports:
- Give the absolute change in its units (pesos, complaints, people).
- Give the relative change when the base matters to the reader.
- Give both levels, before and now, so anyone can redo the math.
Complaints about double charges went from 3 to 9 during the year (they tripled), out of about 40,000 receipts.
If you have a report that brags about a huge percentage, ask your Maestro what you'd need to judge it.
Try it
The query below sorts the branches by their percent change, and Ceiba Express comes out first. Add the change in pesos and sort by it. The subtraction is as simple as it sounds: ventas_2025 - ventas_2024. Make it the second column, named cambio_pesos, and change the ORDER BY so it sorts by cambio_pesos from highest to lowest.
Return sucursal, cambiopesos (ventas2025 minus ventas2024) and cambiopct, in that order, sorted by cambiopesos from highest to lowest and then by sucursal. You're done when Centro is at the top with 2600000 and Chapultepec at the bottom with -1800000.
Your turn
Return sucursal, cambio_pesos (ventas_2025 minus ventas_2024) and cambio_pct, in that order, sorted by cambio_pesos from highest to lowest and then by sucursal. You're done when Centro is at the top with 2600000 and Chapultepec at the bottom with -1800000.
Tables: sucursales (sucursal, municipio, ventas_2024, ventas_2025, clientes_2024, recompraron_2024, clientes_2025, recompraron_2025)
sucursales · 24 rows
| Column | Type |
|---|---|
| sucursal Nombre de la sucursal. | VARCHAR |
| municipio Municipio (ficticio) donde está. | VARCHAR |
| ventas_2024 Ventas del año 2024, en pesos. | BIGINT |
| ventas_2025 Ventas del año 2025, en pesos. | BIGINT |
| clientes_2024 Clientes con tarjeta que compraron en 2024. | BIGINT |
| recompraron_2024 De esos clientes, cuántos volvieron a comprar en menos de 90 días (2024). | BIGINT |
| clientes_2025 Clientes con tarjeta que compraron en 2025. | BIGINT |
| recompraron_2025 De esos clientes, cuántos volvieron a comprar en menos de 90 días (2025). | BIGINT |
First rows
| sucursal | municipio | ventas_2024 | ventas_2025 | clientes_2024 | recompraron_2024 | clientes_2025 | recompraron_2025 |
|---|---|---|---|---|---|---|---|
| Centro | Ciudad Ceiba | 41200000 | 43800000 | 9800 | 2840 | 10400 | 3120 |
| Chapultepec | Ciudad Ceiba | 27900000 | 26100000 | 7100 | 2200 | 6900 | 2140 |
| Plaza Norte | Ciudad Ceiba | 9400000 | 10100000 | 2600 | 960 | 2750 | 1070 |
Every run starts from fresh copies of the course's tables, so try anything. Tab indents; to leave the editor, press Escape, then Tab.
Ready to run your query.
With the table sorted by pesos, the podium changes: Centro, Ceiba Express, Malecón. And at the bottom, something shows up that the percentages were hiding: Chapultepec lost 1.8 million, by far the chain's biggest drop. If management looks only at percentages, Chapultepec (−6.5%) looks like a smaller problem than Los Arcos (−10.5%). In pesos, its drop is nine times Los Arcos's.
Neither order is the right one. They answer two questions: which branch changed the most for itself, and which one moved the chain the most.