Research Article
Using the Quarterly Compound Fractional Grey Model to Predict the Air Quality in 22 Cities of China
Table 4
The fitting results of the two models (unit: μg/m3).
| Quarter | Actual value | GM (1, 1) | QCGM (1, 1) | New sequence | GM (1, 1) | QCGM (1, 1) |
| 2015-1 | 68 | 68 | 68 | 75 | 75 | 75 | 2015-2 | 54 | 60 | 54 | 54 | 60 | 49 | 2015-3 | 50 | 59 | 49 | 50 | 59 | 42 | 2015-4 | 68 | 59 | 69 | 68 | 59 | 65 | 2016-1 | 61 | 58 | 66 | 61 | 58 | 67 | 2016-2 | 52 | 58 | 54 | 52 | 58 | 56 | 2016-3 | 47 | 57 | 48 | 47 | 57 | 51 | 2016-4 | 73 | 57 | 67 | 73 | 57 | 72 | 2017-1 | 68 | 56 | 64 | 68 | 56 | 69 | 2017-2 | 56 | 56 | 52 | 56 | 56 | 55 | 2017-3 | 50 | 55 | 46 | 50 | 55 | 48 | 2017-4 | 61 | 55 | 64 | 61 | 55 | 66 | 2018-1 | 56 | 54 | 60 | 56 | 54 | 62 | 2018-2 | 49 | 54 | 49 | 49 | 54 | 48 | 2018-3 | 41 | 53 | 43 | 41 | 53 | 42 | 2018-4 | 60 | 53 | 60 | 60 | 53 | 56 | 2019-1 | 56 | 52 | 57 | 56 | 52 | 52 | 2019-2 | 44 | 52 | 46 | 44 | 52 | 40 | 2019-3 | 42 | 51 | 41 | 42 | 51 | 34 | 2019-4 | 59 | 51 | 56 | 59 | 51 | 46 |
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