Li Hongbin, Qian Zhijuan, Gu Jianming, Feng Haijuan, Wang Jie.
Objective To predict the missing values of primary physical development of children in nine suburban areas of China in 2015. Methods The original sequence based on birth body mass, length and head circumference of suburban children from 1975 to 2005 was established in nine cities of China, or introduced the average weakening buffer operator, and the missing values of primary physical development in 2015 were predicted by the mean GM (1,1) model. The accuracy level of the models were judged by absolute degree of incidence(σ), mean relative error(α), mean square deviation ratio(C), and small error probability(P). Results The development coefficient of GM (1,1) for the birth body mass of rural boys was a=-0.015 3, grey action quantity was b=3.146 3, σ=0.999 7, α=0.004 5%, C=0.004 0, P=1.00, and the predicted value of boy′s birth body mass in 2015 was 3.371 2 kg; the girl′s model introduced the 2 order weakening buffer operators, the development coefficient of GM (1,1) for the birth body mass of rural girls was a=-0.001 7, grey action quantity was b=3.172 4，σ=0.999 5，α=0.039 1%， C=0.185 0，P=1.00, and the predicted value of girl′s birth body mass in 2015 was 3.196 2 kg. The development coefficient of GM (1,1) for the birth length of rural boys was a=-0.002 0, grey action quantity was b=50.050 3, σ=0.999 9, α=0.000 1%, C=0.000 5, P=1.00, and the predicted value of boy′s birth length in 2015 was 50.500 3 cm; the development coefficient of GM (1,1) for the birth length of rural girls was a=-0.002 0, grey action quantity was b=49.450 1, σ=0.999 9, α=0.000 1%, C=0.000 6, P=1.00, and the predicted value of 〖JP2〗girl′s birth length in 2015 was 49.900 3 cm. The boy′s model introduced the 2 order weakening buffer operators, the development coefficient of GM (1,1) for the birth head circumference of rural boys was a=-0.000 3, grey action quantity was b=34.164 9, σ=0.998 4, α=0.014 4%, C=0.299 4, P=1.00, and the predicted value of boy′s birth Head circumference in 2015 was 34.214 8cm; the girl′s model introduced the 4 order weakening buffer operators, the development coefficient of GM (1,1) for the birth head circumference of rural girls was a=0.000 3, grey action quantity was b=33.732 0，σ=0.999 3, α=0.004 9%, C=0.198 1, P=1.00, and the predicted value of girl′s birth head circumference in 2015 was 33.692 4 cm. Conclusion The Mean GM (1,1) has high accuracy and reliable prediction results.
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