Data & Analytics
How to set up a live metrics chart
A live chart is only useful if it answers a question and refreshes at a sensible pace. This guide walks through three decisions, with a worked example from a small online shop.
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Step one: pick one question and one metric
Start with a single question the chart must answer, then choose the one measurement that answers it. Example: a small online shop wants to know whether checkout is healthy during a promotion. The question is whether orders are arriving at the usual pace, so the metric is orders per minute. Resist adding revenue, visitors and errors on day one; each extra line makes the key signal harder to read. Write the question above the chart as its title, such as Are orders arriving normally?, so anyone glancing at it knows what to look for.
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Step two: connect the source and set refresh
Next, decide where the numbers come from and how often they update. In the shop example, the order system can send a count each minute to the chart, or the chart can request it on a schedule. Match refresh speed to the decision: a thirty-second update suits a flash sale, while five minutes is plenty for a daily report. Faster is not always better, since constant motion distracts and can strain the source. Check that timestamps use one time zone, and decide how the chart should show a gap if the feed pauses.
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Step three: add a baseline and an alert
A moving line means little without a reference. Add a baseline, such as the typical orders per minute for the same hour last week, drawn as a faint band behind the live line. Then set one alert: if the line falls below the band for ten minutes, notify a named person by message. In the shop example, that person checks the payment page first. Review the chart after the promotion ends, noting false alarms and missed signals, and adjust the band or the delay before reusing the setup for the next campaign.