The graph is not accurate, because GitHub's historical downtime data is not accurate.
For example, here is a Hacker News story about GitHub being down on July 28th 2016: https://news.ycombinator.com/item?id=12178449
Here's GitHub's historical uptime graph (on which this chart is based), saying there was no recorded downtime that day, or in fact that entire month: https://www.githubstatus.com/uptime?page=40
GitHub launched a new status page Dec 2018[1]. It doesn't appear as if any history before Oct 2018 was ported over.
[1] https://github.blog/engineering/infrastructure/introducing-t... [2] https://web.archive.org/web/20181211191456/https://www.githu...
That graph has bugged me since it went viral. The methodology is horseshit: https://github.com/DaMrNelson/github-historical-uptime
Just dumping HARs from devtools from a status site that hallucinates 100% uptime when it has no data. For example, all GitHub services had 100% uptime in June 1996: https://www.githubstatus.com/uptime?page=200
The graph gives GitHub Actions 100% uptime before it launched to GA in November 2019. That factors into the average uptime for every month on the graph before that. It's fully horseshit.
Looks like it's not accurate by under repporting not over reporting. So their down time was likely worse!
We don't have enough data to confirm if it's over or under reporting. This sample size of 1 is enough to prove the data is not perfectly accurate, but it's not enough to prove a skew bias in the data either way.
Oh please, show me a company that has ever over reported their downtime. That's silly.
That's fair. We don't know.
I am making an assumption that if Microsoft saw a lot of false positive outages they would fix that, but might drag their feet if there was an outage that didn't get properly recorded (assuming it's automatic to begin with, it might be that a human needs remember to update it).
Or things didn't change much at all except Microsoft forced them to be more honest in their reporting.
See, I can just as easily make up a story that explains the chart.