you have data on the durations of calls to a call center. What the distribution of these durations might look like?
一般常见的问题是讨论call center单位时间内接收到的电话个数，它服从Poisson distribution这种离散型概率分布。对于duration of calls，我认为它的分布首先一定是long tail的，近似可以认为是log-normal distribution. 如果你感兴趣更具体的research研究，可以参考这篇paper, 里面对 call duration distribution做了很细致的分析: Surprising Patterns for the Call Duration Distribution of Mobile Phone Users