Statistical Analysis of Time Series Count Data： A Study of Consumption of Snake Antivenom in Taiwan
Date Issued
2016
Date
2016
Author(s)
Wen, Chen-Ku
Abstract
Background There are about 1,000 snakebite victims who seek medical treatment in Taiwan every year. Injecting correct snake antivenom timely plays a key role in reducing morbidity and mortality. Among the four types of antivenom currently used, the consumption of antivenin of TR. mucrosquamatus and TR. gramineus(batch code: Freeze Hemorrhagic, abbreviation FH) ,consumed 2,600 doses annually, is the most. Nevertheless, the supply of FH approximately 3,000 doses per year, only enough for human needs. Snakebite incidents show a manifest seasonal pattern. It indicates that the consumption of snake antivenom might change along with the meteorological factors. However, to our best knowledge, we do not find any published literature so far in studying the association between meteorological factors and the consumption of snake antivenom. Aims By using nationwide databases, the objectives of my thesis are (1) to clarify the effects of meteorological factors on the consumption of FH; (2) to evaluate the goodness of fit of different statistical models and to discuss the potential in prediction. Material and Methods This research focuses on the analysis of the FH massive consumption from 2008-2012 National Health Insurance Research Database together with the meteorological data from Central Weather Bureau. Two counties or cities which used FH most during 2008-2012 are selected as the study areas. The correlation between meteorological factors and consumption of FH were analyzed by spearman rank correlation, partial correlation, and autocorrelation. Various goodness-of-fit criteria were used to compare different statistical models, including quasi-Poisson regression model, negative binomial regression model, autoregressive error model, and autoregressive integrated moving average model. Results The two areas consuming FH most are Taichung city and Hualien county between 2008-2012. The results of multiple regression model show that monthly mean humidity and monthly mean temperatures were significant factors in Taichung, and the results in Hualien show that precipitation, first and second-order autocorrelation of consumption of FH were significant factors. After controlling monthly mean humidity, the average monthly consumption of FH in Taichung tend to be lower when monthly mean temperature is higher than 33.6℃ or lower than 23.6℃. The average monthly consumption of FH in Hualien tends to be higher as precipitation increases after controlling first and second-order autocorrelation of consumption of FH. Based on Akaike information criterion and Bayesian information criterion, the ordinary linear regression for the square root of the monthly FH consumption tends to be a better prediction model than other models. Conclusion This research discovered that consumption of FH is affected by different meteorological factors in different cities. Climate factors and the former consumption of FH may be important in building prediction model.
Subjects
snake antivenom
meteorological factors
time series
autoregressive
autoregressive integrated moving average
Type
thesis
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