b.scorecardresearch.comは安全ですか？

Based on user reviews, better be on safe side. On uMatrix I blocked the whole line on feature X domain grid, marking it red. Unfortunately, unlike Chromium based browsers, uMatrix hasn't been updated to FireFox WebExtension format, so I blocked it with the inferior NoScript (not to say it's not a totally professional extension - but NoScript is easier to figure out for average users, and the permission levels, default, allow, temp. allow, block & custom...The latter gives some of same features to allow/block, but if uMatrix is Taj Mahal, NoScript is a mud hut. Maybe I should port it.

It's best to clear cookies and cache after seeing in the corner 'loading b.scorecardresearch.com' because it may use a script to install malware onto your computer. A friend of mine caught at least twenty-two thousand viruses from this, no joke, it seems to be in more and more sites. ScriptSafe can handle it though. If you see their ads /everywhere/ you go you are likely infected.