View Single Post
  #2  
Old 10-04-2012, 11:42 AM
Briscoe Briscoe is offline
Sarnak


Join Date: Aug 2012
Location: The Nameless
Posts: 492
Default

Quote:
Originally Posted by Pan [You must be logged in to view images. Log in or Register.]
Do the math for me. In my experience, it's about a 9pct drop rate from Grachnist spawns. I have a decent enough sample size to say that with some confidence. What are the odds that I don't see one in 128 straight Grachnist kills?

My stats books are in a box that is inaccessable right now and I cannot remember how to set up the question.

Thanks! I'm genuinely interested in re-learning.
My first question would be have you really killed him 128 times? There is a thread from a while back with someone claiming they killed Hadden X amount of times without a Fishbone earring drop, but Uthgaard showed that the person inflated the actual number of Hadden kills by about 50% if I remember right.

Secondly, where is this 9% number coming from? The odds of killing Grachnist 128 times and not seeing the earring are indeed roughly 2%, assuming a 3% drop rate. However, assuming a 9% drop rate, that percentage drops into the 10^-4 range. So changing the probability of a non-drop from 0.97 to 0.91 makes a huge difference.

I suspect that the drop rate is lower than 9%, and/or your 128 figure is perhaps inflated a bit.

The calculation itself is trivial, just take the drop rate percentage to the Xth power.