Charts That Sell · Field notes from the pitch room

Never replace a missing number with zero

Field note #6 · 5 min read

Of all the ways a pitch chart can lie, this is the quietest and the most common. A monthly export arrives, one cell is blank — the warehouse system was down, the deal closed on the 2nd and wasn't booked, the analyst simply didn't fill it in. To make the chart "complete," someone types a 0. Nothing crashes. No error appears. And from that moment the chart is fiction.

Zero is a measurement. Missing is a confession that you don't know. They are not the same number.

What zero actually claims

Putting zero in a revenue cell makes a specific, falsifiable statement: we measured this, and the measured amount was nothing. Zero units shipped. Zero euros earned. Zero customers acquired. Those are rare and meaningful events — a strike, a shutdown, a product launch before its first sale. A blank cell from a broken feed makes none of those claims. It says: the truth exists, and we don't currently possess it.

Everyone in the client's finance department knows the difference. The moment they spot a fabricated zero, they stop reading the chart and start auditing the presenter.

The damage compounds downstream

This isn't philosophical — the zeros quietly break every calculation you built the deck to sell:

• Averages collapse. Six months of €12m average plus a fake zero becomes €10.3m. You've just argued your own client's business shrank 14%.
• Trends fake a cliff. A line chart plunges to the baseline and rockets back — the eye sees a crisis, and worse, a recovery from a crisis that never happened.
• Comparisons invert. Stacked bars, rankings, "best month" picks all re-sort around the phantom.
• Percent growth goes infinite or absurd. Dividing by zero errors out; dividing from zero manufactures an "infinite growth" label in the next period.
• The fabricated story is memorable. People remember the dramatic V-shaped dip. Nobody remembers your footnote.

The honest chart has a gap

Good news: modern chart engines know what missing means. Leave the cell empty and a line chart breaks the line across the absent point — a visible, honest gap — or optionally bridges it with a dashed connector if continuity matters. Bars simply skip the slot; nothing is plotted. The reader sees eleven real columns and one silence. That's exactly what happened. ChartThat keeps blanks as nulls end to end: they parse as missing, the preview shows a gap, and the exported PPTX carries the gap as a genuine empty point with "leave blank" semantics — not a zero.

You can see the difference on the line chart page: the sample month with no value is a break in the line, not a dip to the floor.

If you must show something, annotate — don't invent

Sometimes an audience needs help interpreting a gap. Fine. Then say the true thing: "January data unavailable — billing system migration," set as a direct annotation on the empty slot. If an estimate is genuinely justified (a forecast model, a seasonal apportionment), draw it as an estimate: dashed line, lighter shade, a small "e" marker — visibly distinct from measured reality, with the method named in one line. Estimation is honest when it wears a costume that says so. The sin is dressing a guess up as a measurement.

The deeper pitch logic

Here's why this matters more than chart hygiene: you are selling trust in your solution. The entire commercial premise of a B2B pitch is rely on us. A deck that invents a number to avoid an awkward silence demonstrates the opposite instinct. Admitting a gap — "one month wasn't captured; here it is, marked; we'd instrument it properly on day one" — turns the missing data into evidence of the problem you're proposing to solve. The blank cell stops being a flaw in your chart and becomes a gap in their current setup. Presented honestly, missing data sells data discipline — and data discipline is often exactly the product.

Thirty-second audit

Before every deck: filter the numeric columns for literal zeros and eyeball each one. Real operational zero, or a patched hole? Zeros in counts are often real; zeros in financial or sensor time series on a date that should have data are almost always missing. Ask the source. Delete the digits. Keep the gap.

— Written between pitches. Field note #6 of Charts That Sell. Next: we move up a floor — answer first, with the pyramid principle.