In this model, mean_Ratingi and variance_Ratingi represent hotel
i’s average rating and variance, respectively, in the online user
reviews. Pricei identifies the room rate of hotel i, and the variable
otherFactorsi includes all other factors that can influence online
sales, including the star category of the hotel and the size of the
city in which the hotel is located. In China, the developments of
the economy and e-commerce are imbalance cross the country.
More developed big cities, many of them are near the coast, have
both higher levels of economic and e-commerce development than
smaller and inner cities. So we include the size of the city in term of
GDP ranking as a control variable.