20 November 2025 ยท James Pell
A chart that only plots a site-wide percentage is decoration. The useful version names the category, the listing, the device, and the week the photography changed.
A chart that plots one site-wide conversion line for twelve months can hang in a corridor and still tell a merchandiser nothing. Useful charts are ugly in a particular way: they name the category, then the listing, then the week a photograph or badge changed. Device split matters when the first image is a wide set-shot that collapses on a phone.
We still draw those charts by hand in draft, on paper, before they go into the PDF. That habit catches axes that start at 47% to exaggerate a bump. If the bump is real, it will survive an axis that starts at zero.
Colour on a chart should follow the merchandising question. One colour for the listing under review, grey for the rest of the category, a vertical mark on the week photography changed. Rainbow legends belong in other trades.
If you cannot caption a chart in one sentence that a buyer would recognise, it is not ready for the Monday meeting.