pos samples are selected from all buying records without distinct customer(from 2016-09 till now,about 110 thousand records);neg samples are customer that not in the pos samples(same amount);
(2)
pos samples are selected from all buying records from past six month;neg samples are that not in the pos samples(neg samples may contain ones who bought fund stock before)
(3)
pos samples are selected from all buying records from past year by each month;and neg samples are that not in the pos samples each month (so someone may be pos last month,but neg this year)
when we define neg and pos samples,what is the key or principle or tricks in it?anyone have time come up with suggestion are appreciated.(I am not good enough at English,if there is anything unclear I feel sorrt about and please ask)