{"course":{"slug":"visual-storytelling","title":"Making It Say Something","url":"https://addaly.com/learn/visual-storytelling","level":"beginner","track":"create"},"lesson":{"slug":"data-as-material","title":"A number is a claim with the argument removed","url":"https://addaly.com/learn/visual-storytelling/data-as-material","position":31,"of":64,"minutes":9,"answer":"Every number carries hidden choices of base, window and definition, so state the absolute alongside the relative, name the window, and label the axis.","keyIdea":"Every number carries hidden choices of base, window and definition, so state the absolute alongside the relative, name the window, and label the axis, because no chart is neutral and the honest move is making your choices visible rather than claiming not to have made any."},"body":{"format":"markdown","text":"## Numbers persuade because they look like they have stopped being opinions\n\n\"Sales grew 50%\" reads as a fact. It is a fact about a ratio between two numbers, both of which somebody chose, over a window somebody chose, measured by a definition somebody chose. All three choices are arguments, and all three are invisible in the sentence.\n\nThis matters in two directions. You will be handed numbers by clients and you have to make them into something honest. You will also be tempted, every time, by the version that sounds better.\n\n## Always give the denominator\n\nThe commonest failure is a percentage without a base. \"A 50% increase in customers\" is two customers becoming three. \"Doubled our reach\" is 400 people becoming 800. Neither is dishonest until it is used to imply scale it does not have.\n\nThe repair is a habit rather than a judgement: **state the absolute and the relative in the same sentence.**\n\n> Figure: The same three numbers, with and without a base. Relative alone: Sales grew 50 per cent; We doubled our reach; Complaints fell by a third; Nothing here can be checked. Absolute in the same breath: From 2 customers to 3; From 400 people to 800; From 9 complaints to 6; Both readings see the same pair. Neither column is dishonest until the left one is used to imply a scale it does not have. Stating both is a habit rather than a judgement, which is why it survives a deadline.\n\n> \"From 2 in every 1,000 to 3 in every 1,000: a rise of 50%.\"\n\nThat sentence is harder to misread in either direction. A reader who wants the alarming version and a reader who wants the reassuring version both have to look at the same two numbers. Medical and risk communication has converged on this construction for exactly that reason: relative change alone systematically inflates how large an effect feels, and absolute change alone can bury one that matters.\n\n## Three windows, three different truths\n\nAsk anybody for a growth figure and they will give you the window that flatters. This is rarely deliberate; the flattering window is the one they remember.\n\n- Measured from the worst month, everything is a recovery.\n- Measured from the launch, everything is growth.\n- Measured year on year, seasonal businesses stop lying to themselves.\n\nThe working rule is to **state the window in the same breath as the number**, and to prefer a window chosen for a reason you can say out loud: a full year because the business is seasonal, since the new premises because that is the change being discussed. If the number only works in one particular window, you have found something out about the number.\n\n## The chart is an argument too\n\nA line chart makes three editorial decisions before anyone reads it: where the vertical axis starts, how wide the time span is, and what is left off.\n\n- **A truncated vertical axis** (starting at 94 rather than 0) magnifies small changes into cliffs. There are legitimate uses, mainly where zero is meaningless, such as body temperature or a stock index. There is no legitimate use on a bar chart, because a bar encodes quantity by length, and a bar cut off at the bottom is drawing the wrong length.\n- **Squeezing the horizontal axis** steepens every line. Two charts of identical data at different widths tell different stories, and neither is false.\n- **What is missing** is the hardest to see. A chart of surviving businesses is a chart with the failures deleted, and the shape it draws is the shape of survival, not of outcome.\n\n## Check the definition before you draw anything\n\n\"Customers\" can mean accounts, people, households, or orders. \"Active users\" depends entirely on a period somebody picked. \"Response time\" can be a mean, which one bad week ruins, or a median, which hides the bad week entirely.\n\nAsk two questions of every number you are given: **counted how, and from what?** A surprising proportion of the time the person supplying the figure does not know, and finding out changes it. That is not an obstacle to the work; it is the most useful hour you will spend on it, because the number that survives the question is the one you can put on a wall.\n\n## The free path is complete\n\nYou do not need paid software for any of this. LibreOffice Calc and Google Sheets do the arithmetic. Datawrapper's free tier produces clean, accessible, embeddable charts and defaults to sensible axes. For anything programmatic, Python with pandas and matplotlib, or R, cost nothing and are what most published analysis is actually made with. If you are on a phone, Google Sheets and Datawrapper both work in a mobile browser.\n\n## Where this stops being technique\n\nThere is a line between choosing a clear presentation and choosing a flattering one, and it is not always obvious where you are standing. A usable test: **would you be comfortable if the audience saw the other defensible presentation next to yours?** If the answer is no, you have not designed a chart, you have built an argument that depends on the alternative being hidden.\n\nThe honest limitation is that no presentation is neutral. Every chart has an axis, a window and an omission, and a person who says their version is the data is either inexperienced or selling something. What you can do is make your choices visible (label the axis, state the window, say what is excluded) so a reader can disagree with the framing rather than only with the conclusion."},"check":{"question":"Why is a truncated vertical axis defensible on a line chart of a stock index but not on a bar chart of quarterly sales?","options":[{"text":"Stock indices change too fast for a zero baseline to stay useful, while sales figures are stable enough to fit one.","correct":false,"tempting":"Explains by volatility rather than by encoding; a stable index would still be fine truncated and a volatile sales bar chart still would not."},{"text":"A bar encodes quantity by its length, so cutting the baseline draws a length that no longer matches the value.","correct":true},{"text":"Bar charts are read by general audiences while index charts are read by specialists who can correct for the axis.","correct":false,"tempting":"Assumes expertise cancels a visual distortion; the effect of a truncated axis is robust and does not depend on the reader's sophistication."},{"text":"Financial conventions permit truncation, and business reporting conventions do not, so the difference is one of professional norms.","correct":false,"tempting":"Appeals to convention instead of the graphical reason, which leaves you unable to judge any chart type the conventions do not cover."}]},"prev":{"slug":"found-material-and-licences","title":"Free to download is not free to use","url":"https://addaly.com/learn/visual-storytelling/found-material-and-licences"},"next":{"slug":"the-material-audit","title":"Find the missing shot now, not in the edit","url":"https://addaly.com/learn/visual-storytelling/the-material-audit"},"authorship":"Founder and series editor: Dr Mustafa Mun. Written by AI models to a written standard. Exam keys checked blind by a second model: 3,665 of 3,666 agreed. Academic review invited.","review":{"status":"Draft, open for academic review"},"cite":"Addaly (2026) 'A number is a claim with the argument removed', in Making It Say Something. Edited by M. Mun. Addaly. Available at: https://addaly.com/learn/visual-storytelling/data-as-material (Accessed: 13 October 2026).","licence":{"name":"CC BY-NC-SA 4.0","url":"https://creativecommons.org/licenses/by-nc-sa/4.0/"},"reader":{"schema":1,"title":"A number is a claim with the argument removed","courseTitle":"Making It Say Something","module":{"index":4,"slug":"getting-the-material","title":"Getting the material"},"answer":null,"keyIdea":"Every number carries hidden choices of base, window and definition, so state the absolute alongside the relative, name the window, and label the axis, because no chart is neutral and the honest move is making your choices visible rather than claiming not to have made any.","hero":{"kind":"figure","figure":{"t":"figure","label":"Figure","figure":{"left":{"title":"Relative alone","items":["Sales grew 50 per cent","We doubled our reach","Complaints fell by a third","Nothing here can be checked"]},"type":"compare","right":{"title":"Absolute in the same breath","items":["From 2 customers to 3","From 400 people to 800","From 9 complaints to 6","Both readings see the same pair"]},"title":"The same three numbers, with and without a base","caption":"Neither column is dishonest until the left one is used to imply a scale it does not have. Stating both is a habit rather than a judgement, which is why it survives a deadline."},"alt":"Figure: The same three numbers, with and without a base. Relative alone: Sales grew 50 per cent; We doubled our reach; Complaints fell by a third; Nothing here can be checked. Absolute in the same breath: From 2 customers to 3; From 400 people to 800; From 9 complaints to 6; Both readings see the same pair. Neither column is dishonest until the left one is used to imply a scale it does not have. Stating both is a habit rather than a judgement, which is why it survives a deadline."}},"blocks":[{"t":"h2","id":"numbers-persuade-because-they-look-like-they-have-stopped-be","runs":[{"text":"Numbers persuade because they look like they have stopped being opinions"}]},{"t":"p","runs":[{"text":"“Sales grew 50%” reads as a fact. It is a fact about a ratio between two numbers, both of which somebody chose, over a window somebody chose, measured by a definition somebody chose. 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A reader who wants the alarming version and a reader who wants the reassuring version both have to look at the same two numbers. Medical and risk communication has converged on this construction for exactly that reason: relative change alone systematically inflates how large an effect feels, and absolute change alone can bury one that matters."}]},{"t":"h2","id":"three-windows-three-different-truths","runs":[{"text":"Three windows, three different truths"}]},{"t":"p","runs":[{"text":"Ask anybody for a growth figure and they will give you the window that flatters. 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Two charts of identical data at different widths tell different stories, and neither is false."}],[{"text":"What is missing","b":true},{"text":" is the hardest to see. A chart of surviving businesses is a chart with the failures deleted, and the shape it draws is the shape of survival, not of outcome."}]]},{"t":"h2","id":"check-the-definition-before-you-draw-anything","runs":[{"text":"Check the definition before you draw anything"}]},{"t":"p","runs":[{"text":"“Customers” can mean accounts, people, households, or orders. “Active users” depends entirely on a period somebody picked. “Response time” can be a mean, which one bad week ruins, or a median, which hides the bad week entirely."}]},{"t":"p","runs":[{"text":"Ask two questions of every number you are given: "},{"text":"counted how, and from what?","b":true},{"text":" A surprising proportion of the time the person supplying the figure does not know, and finding out changes it. 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