Axis crimes

The broken axis

The zero is still there. The middle is missing.

a.k.a. axis break · scale break · the squiggle · the zigzag · discontinuous axis · the gap in the scale

A truncated axis chops the bottom off the scale and announces itself by starting at 94.6. A break does something quieter: it keeps the zero, keeps the top, and takes a slice out of the middle, marking the theft with a small zigzag most readers have been trained to read as a tidying-up. What it removes is not empty space — it is the part of the scale where the difference between the bars actually lives, so lengths on either side of it stop meaning the same thing and the ratio between any two bars becomes whatever the designer’s choice of gap made it. Worse, the two halves are almost never drawn at the same rate: the compressed top buys room for the giant, and every unit up there is worth a fraction of a unit down below.

How to spot it

Look for the break itself — a zigzag, a pair of parallel slashes, or a plain white band running across the plot and through the axis.
Read the tick immediately below the break and the tick immediately above it, then subtract. That number is what the chart deleted.
Compare the deleted stretch against the whole span drawn below it. If more scale is missing than is shown, no length on the chart is proportional to anything.
Measure the rate on each side: count the pixels between two gridlines below the break, then between two gridlines above. They are rarely the same.
A break appearing at all means one bar did not fit. Ask how much it did not fit by — that is the finding the break was inserted to hide.
Broken axes hide in the places where a zero-based axis is a rule: bars, columns, waterfalls. On a line or a dot plot the same gap is a smaller crime, because those marks encode position rather than length.

The fix

A bar’s length is its whole claim, so a bar chart cannot have a break in it — if one value dwarfs the rest, the dwarfing is the story, and the honest chart is the one where four bars are nearly invisible next to a fifth. Where the small values also deserve to be read, give them a second panel at their own zero-based scale, sitting beside the first, with a line saying how far off the panel the big one is: two axes plainly labelled beat one axis quietly interrupted, because the reader can see exactly where the comparison stops. A log axis is the other honest answer for a range that genuinely spans orders of magnitude, provided it is labelled loudly and drawn with dots rather than bars. And if the break is unavoidable — a single outlier in a small-multiple grid, say — print every value on the chart and say in the caption what the gap swallowed, since a number the reader has to take off the labels was never really plotted.

In the gallery

Dark navy board slide, masthead “Five Boroughs Pest & Wildlife · Service-line review · Board pack, Q1 2026”, headlined “Rodent is not the whole business — four more lines are right behind it”. A subhead reads: citywide demand, measured the only way it can be measured — every pest complaint New Yorkers made to 311 in 2025, as logged by the Health Department; one complete year, one agency, one unit, a service request; nothing sampled, nothing weighted, nothing set aside. Filling most of the slide, under the label “311 service requests · NYC Health Department pest complaint types · calendar year 2025”, is a five-bar column chart. The y-axis is labelled 0, 500, 1,000, 1,500 and 2,000, and then, immediately above the 2,000 tick, 30,000, 31,000 and 32,000 — the stretch between 2,000 and 30,000 is replaced by a horizontal band of double zigzag lines running the full width of the plot and through the axis itself. A gold bar for Rodent (rat and mouse sightings, signs, and conditions) is labelled 31,312; it climbs to the top of the lower band, is interrupted by the zigzag, and resumes above it, standing just short of the top of the chart. Four blue bars follow: Pigeon waste (unsanitary pigeon condition) at 1,756, standing a little over half the rodent bar’s height; Standing water (mosquito breeding conditions) at 1,275; Bees & wasps (harbouring bees or wasps) at 548; and Mosquitoes (large number of mosquitoes) at 334. Down the right-hand side, a gold-bordered card reads 1.6× over the line “The rodent line’s lead over pigeon waste, read straight off this chart”. A card headed “Demand by service line · 2025” lists Rodent 31,312, Pigeon waste & odour 1,756, Standing water 1,275, Bees & wasps 548, Mosquitoes 334. A gold card headed “Read-out for the board” says rodent leads but this is not the runaway the trade press describes, that pigeon waste sits just behind it, that standing water and bees are within reach, that mosquito — a seasonal line the firm does not staff at all — is on the same chart as the rest, and recommends two mosquito technicians and a dedicated pigeon crew for FY27. A final card headed “Seasonality” gives 86 rodent complaints per day all year, 1.6 mosquito complaints per day in season, and 0 mosquito complaints between November and March. Three ticked boxes run along the bottom: “Zero-based axis. The scale starts at 0. No truncation, no log scale, no second axis anywhere on this chart”, “Nothing cherry-picked. One complete calendar year, and every complaint type the Health Department files as a pest”, and “One unit throughout. Every bar is the same thing — one service request, logged by one agency, counted once”. A footnote records that the counts were computed by us from NYC 311 Service Requests from 2020 to Present, NYC Open Data dataset erm2-nwe9, queried 21 August 2026, for complaints created between 1 January and 31 December 2025 with responding agency DOHMH, notes that Rodent bundles rat sightings, mouse sightings, signs of rodents and conditions attracting rodents, and states that the slide is a demonstration drawn by us in the manner of a board pack and has never been published anywhere.

The 18-to-1 gap that a zigzag closed to 1.6

The broken axis