Chartbeat creates Spike Alerts when stories receive Social or Links traffic that surpasses a certain "high water mark" threshold. This threshold is automatically calculated by our proprietary algorithm and fine-tuned to each site that we track based on their unique social and external traffic levels.
Our default threshold is set to the 95th percentile, which would mean any story receiving social or externally referred traffic greater than the social/external traffic levels of 94% of other articles on your site would trigger a spike alert. However, our algorithm will automatically raise or lower this threshold to avoid over or under alerting for well-performing articles on your sites.