| getV | Getting asymptotic variance of modified wilcox test statistic | 
| get_quant_H0 | Calculate the necessary quantities under null hypothesis | 
| mod.symm.test | Wilcoxon and Sign tests for symmetry about an unknown center | 
| model | Tree_model | 
| n.symm.test | Sample size determination for nonparametric tests of symmetry when the center is unknown | 
| plasma.silicon | Dataset: plasma.silicon | 
| tree_model_sign | Tree_model_sign |