Anomaly triage: a fixed order for checking a sudden change

Step 1: check the measurement

• Confirm the tracking still fires: the purchase count in the analytics tool should be close to the store's order count, once both use the same definition.
• Check for a recent change to the site, the tag setup, the consent banner or the checkout.
• Check whether the data is complete. A report run before the day ends, or before a delayed source has arrived, shows a false drop.

Step 2: check the store

• Look at stock, prices, shipping and checkout errors on the days of the change.
• Look at which products and landing pages moved. A change concentrated in one product often points to a store cause.

Step 3: check the market

• Check the calendar: a holiday, a sale you know about, a weather or news event, a payday.
• Use the event calendar for the period. An event you did not write down is one you cannot rule out.

Step 4: check the ads

• Look at budget changes, bid changes, paused or ended campaigns, and new creative in the same window.
• Check frequency and creative age before blaming the audience.

Write the triage result down

• Record the time you started, each step checked, what it showed, and the step where the cause was found or the last step checked.
• Limit each step to a fixed time, such as 30 minutes. If a step is not finished, write it down as open.