Board Thread:Special Events/@comment-121.7.198.251-20151129015829/@comment-26357385-20151203093413

110.175.24.179 wrote: Anyone good with statistic and matlab wanna calculate some of the probability of getting a ship with a certain number of runs? I.e. I'm doing   1-binocdf(0,65,0.01103) on matlab to estimate that i'd need at least 65 runs (S ranks only) for a 50% chance of owning at least 1 Prinz Eugen. Is this mathematically incorrect? Not claiming to be an expert in statistics, but I think we can do some calculations with the principle of probability. From kancolle-db, the drop rate for Prinz is 1.25% at Easy S-Rank, so the chance of NOT dropping her is 98.75%. So, let's assume the number of successful runs expected to have 50% probabilty of NOT dropping her to be 'n':

0.9875^n = 0.5

n = 55 (approx.)

Since a 50% probability   of NOT dropping Prinz is the same as a  50% probability   of getting at least 1 Prinz,  an average player is expected to drop Prinz at 55 S-ranks WITH DROPS. But since the node is not a boss node and does not always grant you drops, you may want to double this value, assuming the node has 50% chance of dropping a ship.

If we take other factors into account (e.g. unable to get S-rank at node, forced retreat en-route), the number of runs you need may be much higher, depending on how good your setup is.