Sale weeks versus ordinary weeks in device comparison

Black Friday, January sales, and mid-season promotions change who shows up and on which device. Phones often surge with opportunistic traffic; computers may hold the higher-intent buyers who already compared prices at lunch.

Our practice

We never average a sale week into an ordinary baseline without labelling it. A conversion comparison study usually shows two boards: promotional window and control window. If budget only allows one window, we pick the one that matches the decision — planning a sale creative? Use sale weeks. Fixing everyday checkout friction? Use ordinary weeks.

A quick check you can do tomorrow

Pull last year’s same calendar weeks, split by device, and look at purchase rate — not revenue alone. Revenue hides traffic volume. Rate tells you whether the path itself behaved differently when the posters went loud.