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Go-live & after

Traffic drop

Also known as: Traffic-Einbruch analysieren

A traffic drop is a marked decline in visits to a website. In SEO the term usually refers to organic traffic from search. Comparing the timing, the affected pages and the traffic sources narrows down the cause.

What are the possible causes?

Google’s guide to debugging drops in Search traffic names these categories:

  • algorithmic updates, including core updates
  • technical issues that affect crawling, indexing or serving, such as server availability, robots.txt fetching or “page not found”
  • security issues such as malware or phishing
  • spam policy violations, with or without a manual action
  • seasonality and changing user interest
  • site moves and migrations that change URLs

Google also suggests checking the Search Console Data Anomalies page, because a drop can come from a change in data processing or a logging error.

How does the analysis start?

In the Search Console Performance report, Google recommends selecting 16 months, so that a yearly pattern is visible. Then compare the drop period with the previous period or the same period a year earlier, and look at queries, URLs, countries, devices and search types separately. Google Trends shows whether interest in a topic fell across the web.

If impressions stay the same and clicks fall, Google points to the page title and snippet, or to more appealing rich results from other sites. A misplaced noindex depends on Google crawling the page again, so traffic falls more slowly than after a site-wide outage.

Example (fictional)

Clicks on category pages fall from a Monday on. Crawl stats show more 5xx responses since the same day, and a release ran on the weekend. The deployment is the likely cause.

Normal range, outlier, false alarm (example data, made up)Line chart with made-up example data over 56 days, shown as an index (100 = a typical weekday). An expected band shows the normal range for each weekday; at weekends it is lower. The line mostly moves within the band, which is normal noise. On day 24, a public holiday, the value drops below the band. This triggers an alert even though the cause is known, so it is a false alarm. From day 44 the value drops sharply and stays below the band. That is a real drop and a justified alert. The lower edge of the band serves as the threshold.Example data, made upExpected bandMeasured valueAlertFalse alarmIndex(100 = typical weekday)6080100120Day 1Day 14Day 28Day 42Day 56lower edge= thresholdnormal noise within the bandDay 24, public holiday: below theband, cause known → false alarmfrom day 44: sharply andpersistently below the band→ alertMade-up values for illustration. Band = expected value per weekday ± tolerance.Example data, made up.
Made-up example data. A metric mostly moves within its expected range. A public holiday falls outside the band and triggers a false alarm, while a sustained drop triggers a justified alert. Example based on practice, not a standard method. Schematic illustration.

Sources

  1. Debugging drops in Google Search traffic – Google Search Centraldevelopers.google.com
  2. Site moves and migrations – Google Search Centraldevelopers.google.com
  3. Diagnosing Traffic Drops During a Crisis – Moz (secondary, 2020)moz.com

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