Ole Begemann ran Google Analytics on oleb.net from March 2011 until January 2018. On 25 May 2018, GDPR day, he wrote up the switch to a self-hosted Matomo install. Matomo was still often called Piwik then. He uses both names.
The post is his. He apologizes for leaving GA on the site as long as he did. He wanted it harder for a large ad company to follow people across sites, and a shared analytics host works against that. He says he was lazy about removing it.
The Google Analytics → Matomo playbook is the import and the metric-diff checklist. Begemann’s useful measurement is a one-month overlap, not an imported history.
What he collects now
He still wants numbers. The list is short. Page views and visitors over time. Which posts get read. Referring sites. Countries.
He says none of that needs a visitor trail. It is close to a web server log. Matomo is configured to anonymize IP addresses and to skip cookies, so a return visit is not tied to an earlier one. It also honors the browser Do Not Track header. He tells people to turn that on if they want out.
He also assumes ad blockers will block Matomo, and he tells readers to use one. So the install is self-hosted, cookieless, and easy to block. He is fine with under-counting.
The one-month gap
He ran Matomo and Google Analytics together for a month, to see how the reports differed. Matomo’s pageviews were about 11 percent lower than Google Analytics in that window.
He expected the opposite. More people block GA, so Matomo should have been higher if the only difference was blockers. On 31 May 2018 he added a note. Emilio Pavia suggested the gap came from honoring Do Not Track. Begemann says he had not thought of that, and he treats it as a good guess. He does not show a second month with DNT turned off to confirm it.
The long tables in the post are the Google Analytics property, April 2011 through December 2017. He says so. They describe the site he had been measuring. The overlap month is a separate figure, about 11 percent, and it is the only Matomo comparison he publishes.
He does not describe the Matomo install, the server, or a GA history import. “Quite easy” is the whole setup section. There is no bill, because he hosts it himself and does not price the machine.
What I would copy
Overlap the two collectors for a real month before you delete the old tag. His 11 percent is the kind of gap you want to see while both scripts are still on the page.
Write down which privacy settings were on during that month. DNT was the explanation he missed at first. Cookie-less tracking and IP anonymizing belong in the same note, or the next person will “fix” a gap that is the configuration.
Keep the old annual history labeled as GA. His charts stop at December 2017 and never claim to include Matomo. If you need those years inside Matomo, that is a separate import, and this post does not do it.
Decide which questions you still ask. He kept page views, posts, referrers, and countries. He dropped the visitor path on purpose, by turning cookies off.
The Google Analytics → Matomo playbook is where the historical import and the report differences are spelled out. Begemann’s post is the overlap, the 11 percent, and the DNT guess.