Alerts that don't cry wolf

Every team that sets up alerts goes through the same three weeks. Week one, they set a dozen thresholds and feel in control. Week two, the phone buzzes six times a day. Week three, somebody mutes the channel, and the one alert that mattered arrives into silence.

The problem is almost never the alert. It is the threshold. A fixed number — “tell me if revenue drops below £1,500 a day” — ignores that Mondays are always quiet and Saturdays are always busy. It fires every Monday and never on the Saturday that was actually bad.

Set thresholds from your own history

Halvard suggests thresholds from the last eight weeks of the same metric, for the same weekday and hour. A quiet Monday is compared with other Mondays. An alert fires when today sits outside the normal range for a day like today, not outside a line someone drew once.

You can still set a fixed number where one makes sense. Stock below 40 units is a fixed number because the supplier’s lead time is fixed. Revenue is not.

Three rules we give every customer

• Every alert has an owner. It goes to the channel or the person who can act on it, not to everyone. If nobody would do anything differently after reading it, delete it.
• Wait before you shout. A single slow hour is noise. Most rules should need the condition to hold for two readings in a row before they fire.
• Say what normal looks like. The message should carry the number, the usual range and a link to the chart. “Refunds £420 today, usually £90–£160” can be acted on. “Refund alert” cannot.

A starting set

For most shops, four alerts cover it: stock cover under seven days on a best seller, refunds above the usual range, a card terminal silent for 40 minutes in opening hours, and first reply to customers above four hours. Start there. Add a fifth only when you have missed something the four would not have caught.