Statistical Analysis Nominal variables will be analyzed using percentage frequencies, X2 test or Fisher exact test. Numeric variables using Student's t test for independent samples and ANOVA with post hoc Scheffe test. U Mann Whitney and Kruskal Wallis tests will be used as long as data do not conform to normal distribution. All values of p <0.05 will be considered statistically significant. The analysis will be perform with statistical program SPSS v. 18 for Windows program.