Reading a volume curve
Slides done? Here’s the same idea in a bit more depth — the part worth keeping.
In depth: why a curve is never just one thing
When a volume history is plotted as a single line, the eye sees chaos — a jagged thing that jumps around with no obvious rule. The skill of a forecaster is to stop seeing one line and start seeing the four separate, well-behaved patterns stacked inside it. Each one moves on its own clock, each has a different cause, and each needs handling differently. Pull them apart and the chaos resolves into something you can actually predict.
The four clocks
Trend is the slowest hand — the drift over months and years as your customer base grows or shrinks, or as contacts migrate from phone to digital. Seasonality is the repeating within-year shape: the January spike, the summer lull, the pre-Christmas wall, the same broad story every year. Day-of-week is the fingerprint inside a week; for most operations Monday is reliably the heaviest day and the weekend the lightest, and that shape barely changes. Intraday is the fastest hand — the shape inside a single day, the mid-morning peak and lunchtime dip — and it’s the one that actually decides how many people you need in each half-hour.
Why it matters that they compound
The patterns don’t add, they multiply. Your busiest interval of the year is the moment all four hands point the same way at once — an upward trend, the seasonal peak, the busiest weekday and the daily spike, stacked. That’s why a flat percentage uplift quietly fails: it spreads evenly across a curve whose peaks are driven by layers piling up, so it under-staffs the moments that matter most and over-staffs the quiet ones. Naming which patterns are present also tells you which method you need — a simple average can cope with day-of-week, but it can’t see a trend or a moving seasonal peak.
The principle to remember: decompose before you forecast. Name the patterns that are actually present in your data, and make sure your method handles every one you find — not just the surface wiggle.
Quick quiz
Five questions. Pick an answer to each, then check your score.
1. How many patterns are typically layered into one volume curve?
Four: trend, seasonality, day-of-week and intraday. Good forecasting starts by pulling them apart.
2. The slow drift over months and years is…
Trend — a growing or shrinking base, or channels migrating over time.
3. The January spike and pre-Christmas wall are examples of…
Seasonality — it repeats on a yearly cycle, so last year (adjusted for trend) is your best guide.
4. Which pattern most directly drives interval-level staffing?
Intraday. The mid-morning peak and afternoon hump are what you actually staff to, interval by interval.
5. Why decompose a curve before forecasting?
So the method matches the data. A method that ignores a pattern that’s present will be systematically wrong.
Try it on real data with the volume forecaster, or go deeper in The Forecasting Masterclass.