To clarify how flagging works on HN: Flagging only hides a comment once "enough" users flag it, and even then remains visible to users with the showdead option set in their profile.
For that matter a lot of posts get suppressed right away, particularly from people who visit HN and immediately start posting stories from the same blog over and over again.
If the [flagged] logic is simply "flags >= N", then of the subset of samples that are flag-killed with your involvement, you will be final flag in 1 of N of those.
The null hypothesis is "this experiment converges to a reciprocal integer".
I guess this might give you a pretty nice upper estimate though. Unless N is very high / very few users use the feature, and you are frequently much later to the scene as the average user of the feature. Then N may be underestimated.
And certain topics are likely to be flagged by multiple people, this can be assumed based on the topics that people complain aren't "HN worthy." Anything that can be considered politics, for instance, is probably going to get flagged because of the number of people who don't believe political stories of any kind have a place here.
Amazingly I see articles from Trotskyite populations often don't get flagged because, oddly, Marxism doesn't seem to be political anymore.
PS. @PaulHoule. I flagged it for valid reasons, not just to conduct this experiments, and not because it is political.