In: Statistics and Probability
For this activity, select a recurring quantity from your OWN
life for which you have monthly records at least 2 years (including
24 observation in dataset at least). This might be the cost of a
utility bill, the number of cell phone minutes used, or even your
income. If you do not have access to such records, use the internet
to find similar data, such as average monthly housing prices, rent
prices in your area for at least 2 years (You must note the data
source with an accessible link). Data can also be monthly sales of
some particular commodity. 1.4 Please do the descriptive analysis,
using the method of index number and Exponential Smoothing
individually. And try to explain the pattern you find. 1.5 Use two
methods you learned to predict the value of your quantity for the
next year (12 months). And make comparison with two results.
MONTHS INTERNET BILL
Jan(2018) 1352
Feb 1434
March 1473
April 1879
May 3373
June 2249
July 1327
August 1536
September 1810
October 2060
November 3494
December 2399
Jan(2019) 1410
Feb 1685
March 1724
April 2223
May 3794
June 2662
July 1537
August 1824
September 1888
October 2264
November 3895
December 3124
The Exponential Smoothing method is:
Alpha | 0.3 | ||||||
Data | Forecasts and Error Analysis | ||||||
Period | Demand | Forecast | Error | Absolute | Squared | Abs Pct Err | |
Period 1 | 1352 | 1352 | 0 | 0 | 0 | 00.00% | |
Period 2 | 1434 | 1352 | 82 | 82 | 6724 | 05.72% | |
Period 3 | 1473 | 1376.6 | 96.4 | 96.4 | 9292.96 | 06.54% | |
Period 4 | 1879 | 1405.52 | 473.48 | 473.48 | 224183.3 | 25.20% | |
Period 5 | 3373 | 1547.564 | 1825.436 | 1825.436 | 3332217 | 54.12% | |
Period 6 | 2249 | 2095.195 | 153.8052 | 153.8052 | 23656.04 | 06.84% | |
Period 7 | 1327 | 2141.336 | -814.336 | 814.3364 | 663143.7 | 61.37% | |
Period 8 | 1536 | 1897.035 | -361.035 | 361.0355 | 130346.6 | 23.50% | |
Period 9 | 1810 | 1788.725 | 21.27518 | 21.27518 | 452.6334 | 01.18% | |
Period 10 | 2060 | 1795.107 | 264.8926 | 264.8926 | 70168.1 | 12.86% | |
Period 11 | 3494 | 1874.575 | 1619.425 | 1619.425 | 2622537 | 46.35% | |
Period 12 | 2399 | 2360.403 | 38.59739 | 38.59739 | 1489.758 | 01.61% | |
Period 13 | 1410 | 2371.982 | -961.982 | 961.9818 | 925409 | 68.23% | |
Period 14 | 1685 | 2083.387 | -398.387 | 398.3873 | 158712.4 | 23.64% | |
Period 15 | 1724 | 1963.871 | -239.871 | 239.8711 | 57538.14 | 13.91% | |
Period 16 | 2223 | 1891.91 | 331.0902 | 331.0902 | 109620.7 | 14.89% | |
Period 17 | 3794 | 1991.237 | 1802.763 | 1802.763 | 3249955 | 47.52% | |
Period 18 | 2662 | 2532.066 | 129.9342 | 129.9342 | 16882.9 | 04.88% | |
Period 19 | 1537 | 2571.046 | -1034.05 | 1034.046 | 1069251 | 67.28% | |
Period 20 | 1824 | 2260.832 | -436.832 | 436.8322 | 190822.4 | 23.95% | |
Period 21 | 1888 | 2129.783 | -241.783 | 241.7826 | 58458.81 | 12.81% | |
Period 22 | 2264 | 2057.248 | 206.7522 | 206.7522 | 42746.47 | 09.13% | |
Period 23 | 3895 | 2119.273 | 1775.727 | 1775.727 | 3153205 | 45.59% | |
Period 24 | 3124 | 2651.991 | 472.0086 | 472.0086 | 222792.1 | 0.1510911 | |
Total | 4805.313 | 13781.86 | 16339605 | 592.22% | |||
Average | 200.2214 | 574.2441 | 680816.9 | 24.68% | |||
Bias | MAD | MSE | MAPE | ||||
SE | 861.8058 | ||||||
Next period | 2793.59399 |
The regression method is:
r² | 0.163 | |||||
r | 0.404 | |||||
Std. Error | 747.260 | |||||
n | 24 | |||||
k | 1 | |||||
Dep. Var. | Data | |||||
ANOVA table | ||||||
Source | SS | df | MS | F | p-value | |
Regression | 23,93,544.5435 | 1 | 23,93,544.5435 | 4.29 | .0504 | |
Residual | 1,22,84,729.4565 | 22 | 5,58,396.7935 | |||
Total | 1,46,78,274.0000 | 23 | ||||
Regression output | confidence interval | |||||
variables | coefficients | std. error | t (df=22) | p-value | 95% lower | 95% upper |
Intercept | 1,613.7283 | |||||
t | 45.6217 | 22.0355 | 2.070 | .0504 | -0.0771 | 91.3205 |
Predicted values for: Data | ||||||
t | Predicted | |||||
25 | 2,754.272 | |||||
26 | 2,799.893 | |||||
27 | 2,845.515 | |||||
28 | 2,891.137 | |||||
29 | 2,936.759 | |||||
30 | 2,982.380 | |||||
31 | 3,028.002 | |||||
32 | 3,073.624 | |||||
33 | 3,119.246 | |||||
34 | 3,164.867 | |||||
35 | 3,210.489 | |||||
36 | 3,256.111 |
The regression method is better because it has lower MSE value.