← Back to Dashboard
	SEASONAL DECOMPOSITION ANALYSIS
	Multiplicative decomposition: Demand = Trend × Seasonal × Irregular
	Period	Month	Demand	12-Mo CMA	Ratio (D/CMA)	Seasonal Index	Deseasonalized	Irregular
	1	Jan	4,200			0.823	5,105
	2	Feb	4,350			0.845	5,149
	3	Mar	4,800			0.924	5,197
	4	Apr	5,400			1.032	5,232
	5	May	5,800			1.109	5,230
	6	Jun	6,100			1.158	5,266
	7	Jul	5,500	5,300	1.038	1.037	5,305	1.001
	8	Aug	5,200	5,325	0.977	0.977	5,320	0.999
	9	Sep	4,900	5,350	0.916	0.918	5,335	0.997
	10	Oct	5,100	5,377	0.948	0.950	5,369	0.999
	11	Nov	5,600	5,408	1.035	1.034	5,415	1.001
	12	Dec	6,500	5,442	1.194	1.193	5,451	1.002
	13	Jan	4,500	5,473	0.822	0.823	5,470	0.999
	14	Feb	4,650	5,502	0.845	0.845	5,505	1.000
	15	Mar	5,100	5,531	0.922	0.924	5,522	0.998
	16	Apr	5,750	5,560	1.034	1.032	5,571	1.002
	17	May	6,200	5,590	1.109	1.109	5,590	1.000
	18	Jun	6,500	5,621	1.156	1.158	5,611	0.998
	19	Jul	5,850	5,650	1.035	1.037	5,643	0.999
	20	Aug	5,550	5,675	0.978	0.977	5,678	1.001
	21	Sep	5,250	5,702	0.921	0.918	5,716	1.002
	22	Oct	5,450	5,731	0.951	0.950	5,738	1.001
	23	Nov	5,950	5,763	1.033	1.034	5,753	0.998
	24	Dec	6,900	5,798	1.190	1.193	5,786	0.998
	25	Jan	4,800	5,833	0.823	0.823	5,834	1.000
	26	Feb	4,950	5,865	0.844	0.845	5,860	0.999
	27	Mar	5,450	5,894	0.925	0.924	5,901	1.001
	28	Apr	6,100	5,923	1.030	1.032	5,910	0.998
	29	May	6,600	5,954	1.108	1.109	5,951	0.999
	30	Jun	6,950	5,992	1.160	1.158	6,000	1.001
	31	Jul	6,250			1.037	6,028
	32	Aug	5,900			0.977	6,036
	33	Sep	5,600			0.918	6,097
	34	Oct	5,800			0.950	6,106
	35	Nov	6,350			1.034	6,140
	36	Dec	7,400			1.193	6,205
	SEASONAL INDEX CALCULATION
	Month	Year 1 Ratio	Year 2 Ratio	Year 3 Ratio	Average Ratio	Adjusted Index	Interpretation
	Jan		0.822	0.823	0.823	0.823	Trough
	Feb		0.845	0.844	0.845	0.845	Trough
	Mar		0.922	0.925	0.923	0.924	Trough
	Apr		1.034	1.030	1.032	1.032	Normal
	May		1.109	1.108	1.109	1.109	Peak
	Jun		1.156	1.160	1.158	1.158	Peak
	Jul	1.038	1.035		1.037	1.037	Normal
	Aug	0.977	0.978		0.977	0.977	Normal
	Sep	0.916	0.921		0.918	0.918	Trough
	Oct	0.948	0.951		0.950	0.950	Trough
	Nov	1.035	1.033		1.034	1.034	Normal
	Dec	1.194	1.190		1.192	1.193	Peak
	Sum Check					12.000	OK ✓
	METHODOLOGY NOTES
	1. Multiplicative decomposition assumes seasonal effects proportional to trend level.
	2. 2x12 Centered Moving Average smooths seasonal and irregular components.
	3. Seasonal indices sum to 12.0 (normalized). Values > 1.0 = above-average months.