10 days or 30 days are not long enough to change a user. It should be months.
@tranthidung: That would suit me better too, but I tried to pick an interval that would be on the same order as an activity window, so that "H" could change fairly quickly (i.e. better posting habits = better "H" without having to wait too long).
Have you tried the Ignore button? Posts made by Ignored users show a Show/Hide link, so you can once in a while "review" them when they post in a topic you're reading. Or just wait for someone to quote them.
@LoyceV: No, I've never used it. I just assumed if I did that they would disappear from view completely. I probably should have tried it before posting though.
3. How exactly do we get P number?
@ETFbitcoin: For a new activity window, each user's "P" starts at zero. Then "P" gets incremented every time one of their posts is rendered/viewed by a logged-in user, you just have to be careful not to count views more than once per logged-in user.
4. With current formula, H value is likely to be unstable. IMO using scaling such as log scale is needed.
@ETFbitcoin: Yup, I just put in a quick non-linear adjustment on top of a ratio without thinking about it too deeply. If you mean unstable as in "sensitive" or "changes non-smoothly" then that's by design.
Use ignore. On the 1st of each month (or some other time frame which suits your needs), go to "Profile" -> "Ignore user options" and copy your entire ignore list in to a spreadsheet. Then clear your ignore list and start again. Repeat. After 3 or 4 months, any user which has been on every one of your historical ignore lists gets added to a permanent ignore list. From the 1st of each month going forward, instead of wiping your entire ignore list you wipe it and replace it with your permanent ignore list. This means that you aren't condemning any user forever based on a single post which you hit ignore on, but repeated shitposts will eventually get filtered out permanently. Going forward you can give a user "Three strikes" or something similar before adding them to your permanent ignore list.
@o_e_l_e_o: I think I'll start doing that, thanks. I'll also occasionally use Loyce's suggestion about "peeking" at posts every now and then.