SURPLUS/DEFICIT AREA

Use when

• balances that swing between surplus and deficit
• variance vs plan over time where the sign is the story

Do not use when

• all-positive series (CH-TIM-03)
• two series compared (CH-TIM-01)

See instead

• the series never crosses zero: CH-TIM-03
• explaining one period's change by driver: CH-FLO-01

Alternatives

• CH-TIM-01 (no sign story)
• CH-FLO-01 (period deltas as a bridge)

Rules

• y axis symmetric around zero; zero line drawn strong
• surplus filled positive role, deficit filled negative role
• fill splits exactly at the zero crossings
• positive ticks carry a + sign

Never do this

• asymmetric y ranges that shrink one sign
• using it when the series never changes sign
• gradient fills

QA before delivering

• zero line present and strong
• both signs occur
• symmetric scale
• unit once
• source present

Data shape

{
  "title": "Output ran 8% under plan at the June trough",
  "eyebrow": "OUTPUT VS PLAN",
  "source": "Source: production ledger, Dec",
  "unit": "%",
  "x": [
    "Jan",
    "Feb",
    "Mar",
    "Apr",
    "May",
    "Jun",
    "Jul",
    "Aug",
    "Sep",
    "Oct",
    "Nov",
    "Dec"
  ],
  "values": [
    4,
    7,
    5,
    2,
    -3,
    -8,
    -5,
    -1,
    3,
    6,
    9,
    12
  ]
}