The statistical paragraph in material and methods
Data were statistically described in terms of mean ฑ standard
deviation (ฑSD), median and range, or frequencies (number
of cases) and percentages when appropriate. Comparison of
numerical variables between the study groups was done using Student t test for independent samples. For comparing categorical data, Chi-square (v2) test was performed. Exact test was used instead when the expected frequency is less than 5. p values less than 0.05 were considered statistically significant. All statistical calculations were done using computer programs SPSS (Statistical Package for the Social Science; SPSS Inc., Chicago, IL, USA) version 15 for Microsoft Windows (Table 1).