histogram
EvidenceCanvasSeries
One quantity cut into bands that join end to end: each bar is as wide as its band and its area is the band's share, with an optional log axis for bands that widen toward the tail.
Use when the question is how a quantity is spread: annual losses, claim sizes, deal sizes, response times. Each row is a band ($1M..$10M) and its share or count. The x axis is a number line, so bands of different widths draw honestly, and log in the axis line keeps a long tail readable.
riskproportionmetricassessment
When to use
- The shape of a distribution. A histogram earns its slide when the question is how a quantity is spread: where most of it sits and how long the tail is. To compare separate categories, use
bar; for the chance of exceeding each loss, useep-curve. - Bands that widen toward the tail. Loss and claim bands usually widen ($1M, $10M, $50M, $250M). Write them as they are and add
logto the axis line: each bar keeps its true area, and the tail stays readable.
When not to use
- Categories that are not a number line. Regions, products or lines of business are separate things, not bands of one quantity. Use
bar, which leaves gaps between them. - A dash for a range.
$1M-$10Mis not a band: the dash reads two ways beside a negative number. Write$1M..$10M.
Common mistakes
- Expecting equal-height bars for equal shares when the bands differ in width. A bar's AREA is its share, so a band five times as wide with the same share is a fifth as tall. That is what keeps a wide tail band honest; the value printed on the bar is the share.
Authoring
<!-- _class: histogram -->
## Most values sit in the first band.
- `0..10` `45%`
- `10..20` `30%`
- `20..30` `15%`
- `30..40` `10%`Slots
| Slot | Selector | Required | Description |
|---|---|---|---|
title | h2 | yes | Slide heading — say what the shape shows ('Most years stay under $10M; one in thirty tops $100M'), not 'Loss histogram'. |
axes | p > code | no | Optional axis line, as ONE bracketed list in its own paragraph ABOVE the heading: x first, then y — [{Annual loss, $1M..$250M, log}, {Share of years}]. The x member is {name, min..max, log}: the domain is optional and derives from the bands, and log draws a log scale, which needs every band edge above zero. The y member is only a name; a histogram prints its values on the bars, not on a value axis. The paragraph is consumed and painted on the axes. Same idiom as scatter and quadrant. |
bands | ul > li | yes | One li per band, in order along the axis: a range pill and a value pill, in either order — ` $1M..$10M 55% . .. is the only range delimiter. Optional lead text names the band (Attritional $0..$5M 61%); without it the band is named by its range. Bands should join end to end: a gap draws as empty space and an overlap draws two bars over the same stretch, and lint:deck` names both. |
detail | li > ul | no | Optional nested sublist under a band. It opens on hover or tap in Present, and folds into the speaker note in the PDF. |
Data shape
- Each row is a band
a..b, with b above a, and a value. A row without both, or a band that does not climb ($10M..$1M), is left out. - A value below zero draws with no height, because an area cannot be negative;
lint:deckwarns. For signed values usebar. logneeds the whole axis above zero, the bands and any axis domain; otherwise the chart draws a linear axis, andlint:decksays so.
Anatomy
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