I need to do forecasting of weekly sales using Holt-Winters technique. My data have max 92 weeks of information. I'm planning to consider 72 weeks of data for training & 20 weeks of data for validation & I have only available s/w to do the forecast is R. I'm preparing my training & validation data set using following command
data_ts_s = ts(data$SUM.SALES_UNITS.[c(1:72)], frequency=52) data_ts_c = ts(data$SUM.SALES_UNITS.[c(73:92)], frequency=52)
But for doing forecast using HW, R needs at least 2 periods of data. Can you please help me how to do the forecasting with Holt-Winters technique without 104 weeks of data.