backwards logistic regression

biostat user-friendly biology and medicine oriented statistical software.basic statistics,determining descriptive statistics,normality tests,t-test/pagurova criterion/g-criterion,fisher f-test,correlation coefficients (pearson, fechner) and covariation,anova (manova, glm anova, latin squares analysis),regression analysis,multivariate linear regression,logistic regression,stepwise regression,polynomial regression,cox proportional-hazards regression,nonparametric statistics,2x2 tables analysis (chi-square, yates chi-square, exact fisher test, etc.),rank correlations (kendall tau, spearman r, gamma, etc.),comparing independent samples (mann-whitney u test, kolmogorov-smirnov test, wald-wolfowitz runs test, rosenbaum criterion;kruskal-wallis anova, median test),comparing dependent samples (wilcoxon matched pairs test, sign test, friedman anova, kendall's coeff. of concordance),cochran q test,survival analysis, ,cox regression,probit-analysis,ld50, ld50se, cumulation coefficient, ld100 calculation.