My year has been pretty good in my view, but this month I cant believe what happened. Played something like 8k games this year till november and had a roi about 3% at 15s, now in november I played only 600 games, have close to 55 buy in minus, 25 minus in ev?

I felt really unlucky but can I credit this only to luck or did i forget how to play this game?

Can we expect much bigger variance because of the higher rakes or what?

if those are hypers you are talking about, be thankful your biggest downswing is just 55 bi

There is about a 35% chance of seeing a 55BI swing somwhere an average block of 8000 games, assuming you always have a 3% roi during these. Be careful of losing edge or tilt etc, as if you drop just 1% of roi 55BI swing freqs ramp up to near 60% in every 8k games.
http://www.deucescracked.com/blogs/b...wnswing-Graphs

I was shocked looking at that probability table since I have been running ~70 BI's below EV since I started playing HU HT's in my first 900 games.. like a 2% chance of that happening lol

This sounds a bit like you are confused over the graph and what I define as a downswing. The graph shows the probability of getting a downswing not of running below ev.
A downswing is the amount you fall below your last 'high water mark', as soon as you regain this high water mark the downswing is over (and a new one is round the corner ). The drop ie, No. of BI's from the high water mark to the lowest point reached before regaining this high water mark is the size of the swing.
A downswing is quite different from the amount you run below ev, running below ev is typically a much, much higher probability.
A player with 20% roi would hardly ever see a downswing of 100+BI but would still very, very often run 100+BI below expectation.

Ah check, that is something else entirely! I used to just use those ters interchangably lol. Now we're on the subject anyways; how much EV variance do you tend to see over in general?

You can use a poker variance calculator to show how things unfold but it is also possible to calculate it with a little bit of maths.

If we know the win probability p and the loss probability q we can calculate the variance of a game, note q = 1 - p.

Variance per game = ([win payout]^2)*p*q

This model assumes your 'edge' never changes which is not true in practice but this model will work for most things if you use the average win rates.

If you play a $0.5 BI with no juice and on average you win 55% and lose 45% then the variance per game is:
V per game = ([0.5 + 0.5]^2) * 0.55 * 0.45 = 0.2475

as Hero wins 55% the mean win per game is (0.55 x $1.00) - $0.50 = $0.05, so roi is $0.05/$0.50 = 10% roi.

If you play enough games the results become closer and closer to the Normal or Gaussian curve and we can use this to tell what you should expect long term if you play say 5000 games.

The variance of n games = the variance per game x n.

So the variance of 5000 games is:
V per 5k games = 0.2475 * 5000 = 1237.5

Now we have the variance per 5k games we can find the standard dev per 5k = Sqrt(Variance), so
sd per 5k = Sqrt(1237.5) = $35.18

5k games at $0.05 profit per game gives us the mean profit we expect as 5000 * 0.05 = $250

So after 5k game we should expect our results to come from a Gaussian 'bell' curve centred on the mean of $250 and we can also tell what the chances of falling to either side of this mean are.
Roughly 70% of the time we should get a result between +/- 1 standard deviations from the mean and so ~70% of the time we get between $250 +/- $35.18
Roughly 95% of the time we should get +/- 2 sd's so $250 +/- $70.36

Very rarely we should see a result outside of +/- 3 sd's from the mean, this happens 100 - 99.73 = 0.27 of one percentage point, or about 1 in 370 times we are outside this range $250 +/- $106

Yes totally normal, here my last last 3 or 4 sessions if it makes you feel any better:

Inst it the same probability to run 100 BI over ev? If yes that is not going to happen very, very often.

Yes, it would be the same above or below.
It is difficult to calculate how often you run above or below the adjusted ev line as you need to know how often you get allin and how much these hands affect the roi, the variable we want to calculate it for.

You can calculate how often you run higher than your own expectation/prediction of roi by using the style I used earlier. I don't think it is that unlikely that you run 100BI above or below this in say a 5000 game stretch.
If you played 5k $5 games with 20% roi you would expect the mean of your profit to be $5000.
So 100 BI is 100 x $5 = $500 above or below this, and I think this happens about 7.5% on the low and also 7.5% above your expectation. So it's about a 1 in 13 event to drop 100BI after 5k games.
I think the frequency you come out over or under adjusted ev will be somewhere in the same ball park but this is more difficult to calculate.