Statistical analysis
polyps
REGRESSION
Qualitative variables were described as absolute frequencies and percentages, quantitative variables as mean and standard deviation or median and interquartile range (Q1:Q3), depending on the type of distribution. In comparisons between groups, we used the Pearson’s chi-square asymptotic and exact tests for quantitative variables, and the Z test for proportion for qualitative variables. For quantitative variables, we used the Mann Whitney test. In the correlation analysis between the variables and the presence of polyps in the group with chromoscopy, we used the univariate and multivariate logistic regression model. The adequacy of the logistic model was evaluated using the Hosmer & Lemeshow test. The significance level used was 0.05. The software used was the SPSS version 20.0 (IBM Corp., Armonk, NY, USA) and Stata 9.1 (StataCorp., College Station, Texas, USA).