Figure presents a dependence of spore distribution on rainfall, classified in four categories. All observations revealed not normal distribution and they were based on five years of measurements. This figure I would like to strengthen using an appropriate statistical test to show statistically significant differences between different amounts of rain that fell within 24 hour...Do you think that Friedman Anova & Kendall's concordance is a right choice? Or is there any other, more suitable test for such analysis? .If there were two categories, instead of four, should I use then a sign test?