Hi,
I’m struggling with forecasting the demand of the customers in a special day of the month. I have the daily data on the customers’ demand, weekend or not (0 and 1), first day of month or not (0 and 1), holiday or not (0 and 1). I used Arima models for forecasting and the result was ok with normal days of the month with very small diffirence between the real demand and the forecasted demand. However, on the first day of every month, due to the monthly promotion, the demand is significantly higher than that on other days. I tried to build a regression model as well. The prediction on the first day of month using regression was better than that using arima model. However, in general, R-squared was just 0.5 which is not high enough. Any one has any ideas which method I can use here to forecast the demand on the first day of the month most accurately? Many thanks!