When looking at the charts shown on the Operations Dashboard, the data (response time and availability) are not identical to those on the linked test chart.
Some small amount of discrepancy should be expected between the Operations Dashboard and Test Charts.
The Operations Dashboard pulls aggregated data from a slightly different source, which is refreshed every 5-10 minutes; Test Charts pull "live" data directly from the nodes.
The Operations Dashboard shows the aggregate information only for the nodes which are in an alert state, whereas the Backbone chart shows the average for all nodes being tested against. The two will often not match precisely, especially if the number of alerting nodes is fewer than the total number of nodes being tested.