问一道题：NO.PZ201512020300000707 为什么relationship会改变，distribution需要改变呢

问题如下：

Considering industry changes over the past year, one update that Maxwell should make to the simulation model is the:

选项：

choice of the distribution of CSI and ECI.

relation between CSI and occupancy rates.

removal of constraints on occupancy rates.

解释：

B is correct. Even when the data fits a statistical distribution or when historical data distributions are available, shifts in the market structure can lead to shifts in the distributions as well. In some cases, these shifts can change the form of the distribution, and in other cases, they can change the parameters of the distribution. Thus, relations from historical data for an input may change for the next period, affecting the relation between the nightly room rate and CSI, as well as the relation between the occupancy rate and ECI. The constraints on the occupancy rates are necessary because without them, there may be unrealistic results (such as negative rates or rates exceeding 100%). Further, the choice of the distributions of CSI and ECI is not mentioned to be affected by the changes in the industry over the past year; rather, the relation between CSI and occupancy rates may change.