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1.
Preprint in English | medRxiv | ID: ppmedrxiv-20034595

ABSTRACT

During the study of epidemics, one of the most significant and also challenging problems is to forecast the future trends, on which all follow-up actions of individuals and governments heavily rely. However, to pick out a reliable predictable model/method is far from simple, a rational evaluation of various possible choices is eagerly needed, especially under the severe threat of COVID-19 epidemics which is spreading world-wide right now. In this paper, based on the public COVID-19 data of seven provinces/cities in China reported during the spring of 2020, we make a systematical investigation on the forecast ability of eight widely used empirical functions, four statistical inference methods and five dynamical models widely used in the literature. We highlight the significance of a well balance between model complexity and accuracy, over-fitting and under-fitting, as well as model robustness and sensitivity. We further introduce the Akaike information criterion, root mean square errors and robustness index to quantify these three golden means and to evaluate various epidemic models/methods. Through extensive simulations, we find that the inflection point plays a crucial role in the choice of the size of dataset in forecasting. Before the inflection point, no model considered here could make a reliable prediction. We further notice the Logistic function steadily underestimate the final epidemic size, while the Gomertzs function makes an overestimation in all cases. Since the methods of sequential Bayesian and time-dependent reproduction number take the non-constant nature of the effective reproduction number with the progression of epidemics into consideration, we suggest to employ them especially in the late stage of an epidemic. The transition-like behavior of exponential growth method from underestimation to overestimation with respect to the inflection point might be useful for constructing a more reliable forecast. Towards the dynamical models based on ODEs, it is observed that the SEIR-QD and SEIR-PO models generally show a better performance than SIR, SEIR and SEIR-AHQ models on the COVID-19 epidemics, whose success could be attributed to the inclusion of self-protection and quarantine, and a proper trade-off between model complexity and fitting accuracy.

2.
Preprint in English | medRxiv | ID: ppmedrxiv-20023465

ABSTRACT

The outbreak of novel coronavirus-caused pneumonia (COVID-19) in Wuhan has attracted worldwide attention. Here, we propose a generalized SEIR model to analyze this epidemic. Based on the public data of National Health Commission of China from Jan. 20th to Feb. 9th, 2020, we reliably estimate key epidemic parameters and make predictions on the inflection point and possible ending time for 5 different regions. According to optimistic estimation, the epidemics in Beijing and Shanghai will end soon within two weeks, while for most part of China, including the majority of cities in Hubei province, the success of anti-epidemic will be no later than the middle of March. The situation in Wuhan is still very severe, at least based on public data until Feb. 15th. We expect it will end up at the beginning of April. Moreover, by inverse inference, we find the outbreak of COVID-19 in Mainland, Hubei province and Wuhan all can be dated back to the end of December 2019, and the doubling time is around two days at the early stage.

3.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-269959

ABSTRACT

<p><b>OBJECTIVE</b>To analyze pupils' neglect status aged 6-11 years in China's rural.</p><p><b>METHODS</b>According to the principle of multi-stage stratified cluster sampling, to extract 7,943 pupils aged 6-11 years for the survey from 56 primary schools in 28 counties in nine provinces, from December 2012 to March 2013. Proceed questionnaire survey by the scale from "Neglect Evaluation Norms for pupils aged 6-8 years in Rural Areas of China" and "Neglect Evaluation Norms for pupils aged 9-11 years in Rural Areas of China". And analyze neglect rates and neglect degrees of the different grades, gender, family types and different levels of neglect.</p><p><b>RESULTS</b>The total neglect rate of China's rural pupils aged 6-8 and 9-11 years was 40.2% (1,258/3,130) and 42.5% (1,498/3,526) respectively, which differences had no statistical significant (χ2=3.59, P=0.058); the total neglect degree was 46.04±8.87 and 44.78±10.43 respectively, which differences had statistical significant (t=5.01, P<0.001); the differences of neglect rates and neglect degrees between male (41.4% (657/1,587) and 46.28±8.76) and female (39.0% (601/1,543) and 45.78±8.97) of aged 6-8 were all no statistical significant (χ2=1.87, P=0.171; t=1.49, P=0.136); the neglect rates and neglect degrees of male (46.3% (816/1,763) and 45.53±10.11) were higher than female (38.7% (682/1,763) and 44.06±10.69) in the group of aged 9-11, which differences were all statistical significant (χ2=20.84, t=3.97, P<0.001); the male neglect rate in the group of aged 6-8 in social neglect (11.7% (198/1,691)) and the neglect degree in educational neglect (48.09±9.70) were higher than female (9.4% (155/1,648) and 47.37±9.89), which differences were all statistical significance (χ2=14.55, P<0.001, t=2.22, P=0.026), the male neglect rate in the group of aged 9-11 in physical neglect (20.4% (398/1,954)) was higher than female (16.7% (326/1 957)), which differences had statistical significance (χ2=8.92, P=0.003).</p><p><b>CONCLUSION</b>The neglect status of Chinese pupils aged 6-11 years in rural was serious, and we should find out risk factors and provide efficient prevention measures.</p>


Subject(s)
Child , Female , Humans , Male , Child Abuse , China , Physical Examination , Pupil , Risk Factors , Rural Population , Schools , Surveys and Questionnaires
4.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-298899

ABSTRACT

<p><b>OBJECTIVE</b>To develop a standard Neglect Evaluation Scale which is suitable for rural primary school students in China.</p><p><b>METHODS</b>According to the principle of multi-stage stratified cluster sampling, a field investigation was conducted among primary school students in 28 counties from 7 provinces and 2 municipalities. The questionnaires were self-designed, and determined by multiple rounds of pilots and revisions. Among 5 862 students, 2 792 (6-8 years' old) and 3 070 (9-11 years' old) were investigated by using two kinds of Neglect Evaluation questionnaires, respectively. After project analysis, factor analysis, reliability and validity analysis, the reliability and stability of the scale were tested. Then percentile method was used to determine the evaluation standard to develop and finalize the formal scale.</p><p><b>RESULTS</b>The numbers of the remaining items for 6-8 year-old group and 9-11 year-old group is 69 and 58, respectively, both of which contain six levels of neglect, including body, emotion, health care, education, security, and society. 4 times of factor analysis were conducted in both of the two groups. The factor loadings in these two groups were 0.290-0.700 and 0.276-0.729 respectively. Reliability test results showed that the two kinds of scales' Cronbach alpha coefficient were 0.924 and 0.929 respectively, split-half reliability were 0.891 and 0.904 respectively, the retest reliability were 0.559 and 0.892 respectively, the differences were statistically significant (P < 0.05). The retest reliability among 6-8 year-old group in medical neglect level had no statistical significance, but was close to the cut-off point (P = 0.054). The test results of external validity indicated that both of the two scales could reflect the neglect status of the subjects (P < 0.05), but the subjective and objective evaluation towards neglect were not consistent. The cut-off points for judging whether the children were neglected or not among 6-8 year-old and 9-11 year-old groups were 159 and 137 respectively; and the adjusted values were 160 and 135 respectively.</p><p><b>CONCLUSION</b>The two norm scales developed by this study showed good discriminability, reliability, validity, and stability. The norms developed on the basis of the scales was suitable for the situation of rural students in primary schools in China.</p>


Subject(s)
Child , Humans , Child Abuse , China , Factor Analysis, Statistical , Reproducibility of Results , Rural Population , Schools , Students , Surveys and Questionnaires
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