Francisco-José Santonja

Mathematical modelling of social obesity epidemic in the region of Valencia, Spain

In this article, we analyse the incidence of excess weight in 24- to 65-year-old residents in the region of Valencia, Spain, and predict its behaviour in the coming years. In addition, we present some possible strategies to prevent the spread of the obesity epidemic. We use classical logistic regression analysis to find out that a sedentary lifestyle and unhealthy nutritional habits are the most important causes of obesity in the 24- to 65-year-old population in Valencia. We propose a new mathematical model of epidemiological type to predict the incidence of excess weight in this population in the coming years. Based on the mathematical model sensitivity analysis, some possible general strategies to reverse the increasing trend of obesity are suggested. The obese population in the region of Valencia is increasing (11.6% in 2000 and 13.48% in 2005) and the future is worrisome. Our model predicts that 15.52% of the population in Valencia will be obese by 2011. Model sensitivity analysis suggests that obesity prevention strategies (healthy advertising campaigns) are more effective than obesity treatment strategies (physical activity) involving the obese and overweight subpopulation in controlling the increase of adulthood obesity in the region of Valencia.

A mathematical model of the pressure of an extreme ideology on a society

Extreme behavior is produced by small groups, but affects a large amount of people. The fear, the usual strategy of these groups, influences the decisions of the whole population. In this paper we propose a dynamical mathematical model to study the ideological evolution of the population in a region where some groups want to get political goals through violence. After a classification of the subpopulations using data from votes obtained by political parties in general elections, model parameters have been estimated and future tendencies are studied.

Analysing the Spanish smoke-free legislation of 2006: A new method to quantify its impact using a dynamic model

BACKGROUND There are many models that study aspects of smoking habits: the influence of price, tax, relapse time, and the effects of prohibition. There are also studies examining the effects of the Spanish smoke-free law. We wanted to build a model able to separate the effect of the law from the pre-law evolution of smoking habits. METHODS Using data from the Spanish Ministry of Health and Social Policy, we developed a dynamic model of tobacco use. The model projects the evolution over time of the number of non-smokers, smokers and ex-smokers before 2006. Then, we compared the predictions of the model with data for the years after the law came into force, 2006 and 2009. RESULTS We show that smoke-free law has had a significant impact on different sub-populations. The number of ex-smokers increased significantly in 2006 and this increase was maintained in 2009. The number of smokers also decreased significantly in 2006, but in 2009 this returned to its value before the law. Simultaneously, the number of non-smokers decreased in 2009. CONCLUSIONS When the law came into force (2006), its restriction on smoking in public and work places made many smokers decide to give up smoking, decreasing the number of smokers and increasing the number of ex-smokers. In 2009, the majority of those who succeeded in giving up smoking did not return to the habit. However, the smoke-free law had no effect on new smokers and the number of smokers returned to previous levels, whereas the number of non-smokers decreased. Therefore, we can conclude that the law had a very positive effect in the first few years but this has dissipated over time, with the exception of ex-smokers, whose number is still higher than before the law.

Alcohol consumption in Spain and its economic cost: A mathematical modeling approach

In this paper, a mathematical model for alcohol consumption in Spanish population is proposed. Its parameters are estimated by fitting the model to real data from Spanish Ministry of Health. Predictions about the future behavior of the alcohol consumption in Spain are presented using this model. Results are applied to estimate the economic costs (sanitary and non-sanitary) assumed by Spanish society that are derived from this consumption.

Analysing the effect of public health campaigns on reducing excess weight: A modelling approach for the Spanish Autonomous Region of the Community of Valencia

Excess weight is fast becoming a serious health concern in the developed and developing world. The concern of the public health sector has lead to the development of public health campaigns, focusing on two-fold goals: to inform the public as to the health risks inherent in being overweight, and the benefits of a change in nutritional behaviour. Recent studies indicate that the effects of the average public health campaign on the target community is around 5%. In this study we aim to quantify the effect of different public health campaigns on lifestyle behaviour in the target populations in order to bring about weightloss in a significant number of people over the next few years. This study is based on recent works that consider excess weight as a consequence of the transmission of unhealthy lifestyles from one individual to another. Following this point of view, first a mathematical model is presented. Then, policies based on public health campaigns addressed to stop people gaining weight (prevention; this type of policy acts on individuals in order to maintain their weight and to stop an increase in weight) and, policies addressed to overweight individuals to reduce their weight (treatment; these campaigns act on overweight and/or obese individuals in order to reduce their weight) are simulated in order to evaluate their effectiveness. The study concludes that combination of preventive plus treatment campaigns are more effective than considering them separately.

A discrete mathematical model for addictive buying: Predicting the affected population evolution

This paper deals with the construction of a discrete mathematical model for addictive buying. Firstly, identifications of consumers buying behavior are performed by using multivariate statistical techniques based on real data bases and sociological approaches. Then the population is divided into appropriate groups according to the level of overbuying and a discrete compartmental model is constructed. The future short term addicted population is computed assuming several future economic scenarios.

The effect of the Spanish Law of Political Parties (LPP) on the attitude of the Basque Country population towards ETA: A dynamic modelling approach

Abstract In June 2002, the Spanish Government passed the “Law of Political Parties” (LPP) with the aim, among others, of preventing parties giving political support to terrorist organizations. This law affected the Basque nationalist party “Batasuna”, due to its proved relation with ETA. In this paper, taking data from the Euskobarometro (Basque Country survey) related to the attitude of the Basque population towards ETA, we propose a dynamic model for the pre-LPP scenario. This model will be extrapolated to the future in order to predict what would have happened to the attitude of the Basque population if the law had not been passed. These model predictions will be compared to post-LPP data from the Euskobarometro using a bootstrapping approach in order to quantify the effect of the LPP on the attitude of Basque Country population towards ETA.

STOCHASTIC MODELING WITH MONTE CARLO OF OBESITY POPULATION

In this paper, we investigate the dynamics of a mathematical model of obesity population within fluctuating social environment. A stochastic differential equation model is constructed by perturbing two social related parameters of the deterministic model with white noise terms characterized by Gaussian distribution having zero mean and unit spectral density. In order to compute the numerical solution of the stochastic models Euler-Maruyama numerical method is used. Confidence intervals for the overweight and obesity childhood population are computed using Monte Carlo method. Analysis of the numerical results reveals that small perturbations on the parameters are not a major driving force for dynamical transitions from the underlying deterministic model. In addition, numerical results indicate a close relationship between the amplitude of the fluctuation of the social environment parameters and the variability of forecasts for the incidence of the obesity in the population.

A probabilistic estimation and prediction technique for dynamic continuous social science models

In this paper, a computational technique to deal with uncertainty in dynamic continuous models in Social Sciences is presented. Considering data from surveys, the method consists of determining the probability distribution of the survey output and this allows to sample data and fit the model to the sampled data using a goodness-of-fit criterion based on the ?2-test. Taking the fitted parameters that were not rejected by the ?2-test, substituting them into the model and computing their outputs, 95% confidence intervals in each time instant capturing the uncertainty of the survey data (probabilistic estimation) is built. Using the same set of obtained model parameters, a prediction over the next few years with 95% confidence intervals (probabilistic prediction) is also provided. This technique is applied to a dynamic social model describing the evolution of the attitude of the Basque Country population towards the revolutionary organisation ETA.

Modelling the dynamics of the students’ academic performance in the German region of the North Rhine-Westphalia: an epidemiological approach with uncertainty

Student academic underachievement is a concern of paramount importance in Europe, where around 15% of the students in the last high school courses do not achieve the minimum knowledge academic requirement. In this paper, we propose a model based on a system of differential equations to study the dynamics of the students’ academic performance in the German region of the North Rhine-Westphalia. This approach is supported by the idea that both good and bad study habits, are a mixture of personal decisions and influence of classmates. This model allows us to forecast the student academic performance by means of confidence intervals over the next few years.