Hi,

When doing the regression analyis using "data analysis" tool I get a different r-square to if I just plot X and Y and look at the trend line and see R-square on the equation - why is this?

Also, how can I actually find the r-square after I have made seasonal forecast - such as:

Time Month Year Demand Deseas Forecast Reseas
1 1 1 120 277.39 215.3983461 93.18057663
2 2 1 330 290.33 239.4410561 272.1599952
3 3 1 440 301.22 263.4837661 384.8727294
4 4 1 220 280.85 287.5264761 225.2305625
5 5 1 330 314.37 311.5691861 327.0634018
6 6 1 500 368.46 335.6118961 455.423241
7 7 1 220 256.40 359.654606 308.5979529
8 8 1 110 264.54 383.697316 159.5495939
9 9 1 220 366.86 407.740026 244.515842
10 10 1 364 360.46 431.782736 436.0195806
11 11 1 303 368.48 455.825446 374.8240724
12 12 1 344 413.97 479.868156 398.7636789
13 1 2 260 601.02 503.910866 217.990091
14 2 2 700 615.85 527.953576 600.09693
15 3 2 900 616.14 551.996286 806.3051487
16 4 2 500 638.29 576.0389959 451.2335312
17 5 2 660 628.73 600.0817059 629.9235382
18 6 2 800 589.54 624.1244159 846.9329235
19 7 2 600 699.27 648.1671259 556.153167
20 8 2 300 721.46 672.2098359 279.519303
21 9 2 400 667.02 696.2525459 417.5326596
22 10 2 720 713.00 720.2952559 727.3631139
23 11 2 600 729.66 744.3379659 612.067163
24 12 2 600 722.03 768.3806759 638.5135194


seasonal factors

Month factor
1 0.432596528
2 1.136647155
3 1.460707561
4 0.783338514
5 1.049729615
6 1.356993737
7 0.858039763
8 0.415821501
9 0.599685649
10 1.009812446
11 0.822297385
12 0.830985915


THANK YOU