What was the forecast error in December 2021? 

What is the CFE for Jan 2019 through Dec 2021?  

What is the MAD for Jan 2019 through Dec 2021? 
 

Scenario B: You are given the following monthly time-series sales and forecast data for the previous 3 years. Month Pd Num Actual Demand Forecast Jan-19 Feb-19 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 123456700 4394 4484 7949 7873 4870 4916 6281 6246 5297 5389 5644 5649 5024 5071 8 7978 7882 Sep-19 9 4918 4949 Oct-19 10 6643 6700 Nov-19 11 5354 5376 Dec-19 12 7867 7861 Jan-20 13 7834 7933 Feb-20 14 4918 4944 Mar-20 15 5761 5822 Apr-20 16 7879 7838 May-20 17 6783 6817 Jun-20 18 5055 5149 Jul-20 19 8227 8220 Aug-20 20 7311 7376 Sep-20 21 5553 5456 Oct-20 22 8112 8211 Nov-20 23 4794 4830 Dec-20 24 6648 6622 Jan-21 25 6009 5999 Feb-21 26 4192 4110 Mar-21 27 7768 7672 Apr-21 28 8351 8419 May-21 29 7809 7834 Jun-21 30 7167 7143 Jul-21 31 8399 8432 Aug-21 32 7023 6993 Sep-21 33 6571 6538 Oct-21 34 5011 4992 Nov-21 35 5134 5164 Dec-21 36 7939 8038