Using the forecast sheet in Excel, the forecasts in weeks 53 to 56 are at 418 (see table). Why are the forecast sheet results (418) different from linear trendline (415 - see below)? What are the causes of the differences? Which method is more accurate - forecast sheet (exponential triple smoothing) or linear trendline? Which one is more recommend in terms of forecasting such demand?

Linear Trendline equation: y= -.0569x + 417.86, using this the weeks 53 to 56 forecasts are at 415.

Week	Demand
1	400
2	450
3	425
4	430
5	460
6	390
7	405
8	416
9	430
10	440
11	395
12	360
13	370
14	410
15	390
16	440
17	460
18	425
19	448
20	462
21	380
22	395
23	414
24	423
25	448
26	422
27	410
28	440
29	427
30	418
31	370
32	380
33	410
34	428
35	412
36	450
37	376
38	360
39	417
40	422
41	440
42	380
43	415
44	432
45	396
46	460
47	422
48	446
49	398
50	428
51	410
52	415