Spatial analysis of the Chinese welfare lottery "double color ball"

The Chinese welfare lottery "double color ball" is a lottery giant in China. In 2011, sales volume is about Y300 million for each drawing, the average monthly sales amount is more than Y3 billion, the highest jackpot is over Y800 million, and there are hundreds of millions of participants with a broad social impact. This, people are concerned aboutwhether thedrawing of "double color ball" is fair or not, that is, whether there is manipulation behind the drawings. This paper based on spatial point pattern analysis methods, by using the package spatstat from R software, taking the nearest neighbor distances (G and F functions), Ripley\´s K-function, Besage\´sL-function, and pair correlation function g(r) methods, studies the fairness of the red ball winning numbers of the "double color ball". The results show that, the red ball winning numbers of "double color ball" is fair on the whole. But for very small datasets, for example, the point pattern formed by 1 or 2 consecutive drawings of winning numbers, it is difficult to decide whether there is complete spatial randomness(CSR) or not.