Environmental Systems Research

Table 2 Results summary—SO₂ data missing in batches

From: Spectral methods for imputation of missing air quality data

	KSVD	DCT	EM	MN	Sp	Lin	NN
MSE (ppb)
Low	80.76	26.48	40.82	95.06	3.89 × 10⁹	81.17	85.39
Mid	98.45	35.11	49.74	101.4	7.9 × 10¹⁰	99.77	101.8
High	110.7	58.59	56.07	104.1	3.29 × 10¹¹	112	112.2
Diff (ppb)
Low	270.9	336.1	270	208.8	3.28 × 10¹⁰	302.2	313
Mid	280.3	356.6	279.3	233.6	5.18 × 10¹¹	304.3	311.2
High	284.3	348.5	286.4	231.9	1.57 × 10¹²	295.5	297.9
STD (ppb)
Low	−2.19	−0.97	−50.42	−8.75	2.91 × 10⁹	−2.59	−0.64
Mid	−16.06	−5.17	−57.39	−30.12	7.73 × 10¹⁰	−16.42	−11.31
High	−45.48	−26.69	−72.05	−57.86	3.62 × 10¹¹	−46.28	−43.49
Time (sec)
Low	387.1	0.2	7.86	9.64 × 10 ⁻⁵	11.7 × 10⁻³	4.78 × 10⁻⁴	26.3 × 10⁻³
Mid	207.7	0.49	8.4	8.89 × 10 ⁻⁵	8.41 × 10⁻³	7.61 × 10⁻⁴	0.16
High	70.06	2.88	7.46	1.02 × 10 ⁻⁴	5.59 × 10⁻³	1 × 10⁻³	0.44

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