Have they changed the enraged/elite formula?

20 days ago, when I boosted something (enraged and Elite), 10-15 elites were coming, out of about 1200 monsters I killed( Two hours boost)!

I noticed a big decrease, because I boosted and on that same average, only 4 came, the same number that came for a friend who also boosted elite/enraged!

I wonder if anyone else has noticed this difference?

Sometimes, I noticed what you mentioned.
But more then half the time this is not the case. Just depends on luck of the draw really. I have experienced 4-5 elites within 15 minutes, also experienced 4-5 elites in a whole 2 hours. Just depends really

Exxec is probably right : RNG.

Based on my bestiary, I would guess normal elite rate is about 1/200.

With the help of a bit of maths I won't explain here, you can deduce that, approximatively, for 1000 mobs, numbers of encountered elites will be, 95% of time, between 0 to 10.

I don't know what is boosted elite rate, but let's suppose it's 1/100.

With the same maths, I obtain that, approximatively, for 1000 mobs, numbers of encountered elites will be, 95% of time, between 4 to 16.

QED.

No Askja they are correct, I did 2 hunts on geck'zas on the bonus elite event and noticed almost no elites were coming from them, this week i did a few hunts without boosting elite and ended up getting close to the same amount of elites 1 out of 350~400, and before it was 1 out of 200 as you mentioned. But the biggest issue is, whenever we boost elites we almost don't notice any difference from where we do not boost them.