Question

Using the method for removing seasonality, what is the the seasonal index for January?

Year	2014	2015	2016	2017	2018
January	34764	37187	38303	39269	42512
February	7233	7745	7977	8336	9000
March	7933	8501	8745	8820	9526
April	8166	8738	9066	9250	9999
May	8400	9001	9201	9501	10159
June	37564	40175	41522	42352	45701
July	46431	49681	51373	52299	56687
August	41298	44171	45500	46623	50249
September	9566	10255	10599	10900	11775
October	5833	6275	6463	6606	7156
November	33365	34694	34525	35223	38100
December	39431	42215	43485	44333	48903

Answer 1

Seasonal index is computed as below:

2018 Average Seasonal Index 1 Year 2 Janua 3 Februa 4 March 5 April 6 Ma 7 June 8 Jul 9 August 10 September 11 October 12 November 13 December 2014 2015 2016 2017 34764 37187 38303392694251238407.0 7233 7933 8166 8400 7745 8501 8738 9001 7977 8745 9066 9201 1.498 0.314 0.339 0.353 0.361 1.617 2.000 8336 8820 9250 9000 8058 9526 8705.0 99999043.8 9501 10159 9252.4 37564 40175 41522 42352 45701 41462.8 46431 49681 51373522995668751294.2 41298 44171 45500 46623 50249 45568.2 9566 10255 10599 10900 11775 10619.0 7156 6466.6 33365 34694 3452535223 38100 35181.4 39431 42215 43485 44333 48903 43673.4 Overall Average 25644.3 0.414 0.252 1.372 1.703 5833 6275 6463 6606 15 16 17 18 19

EXCEL FORMULAS:

Seasonal Index 1 Year 2 Janua 3 Februa 4 Marclh 5 April 6 Ma 7 June 8 Jul 9 August 10 September9566 10255 10599 10900 11775 11 October 5833 6275 6463 6606 7156 12 November33365 34694 34525 35223 38100 13 December 3943142215 43485 44333 48903 2014 20152016 2017 2018 34764 3718738303 39269 42512 7233 77457977 8336 9000 7933 85018745 8820 9526 8166 87389066 9250 9999 8400 9001 9201 9501 10159 37564 4017541522 42352 45701 46431 49681 51373 52299 56687 41298 4417145500 46623 50249 Average AVERAGE(B2:F2) G2/SG$14 AVERAGE(B3:F3) -AVERAGE(B4:F4)G4/$G$14 AVERAGE(B5:F5)G5/$G$14 AVERAGE(B6:F6)G6/$G$14 AVERAGE(B7:F7)G/$G$14 -AVERAGE(B8:F8)G8/$G$14 AVERAGE(B9:F9)G9/$G$14 AVERAGE(B10:F10) G10/$G$14 AVERAGE(B11:F11)G11/$G$14 AVERAGE(B12:F12) G12/$G$14 AVERAGE(B13:F13) G13/SG$14 Overall Average AVERAGE(G2:G13 15 16 17 18

Seasonal index for January = 1.498