Spss for windows 10 v 22

Based on the results of the MAGIC trial, a 5-year survival in the perioperative and adjuvant chemotherapy group was expected to be 50% and 35% in the surgery only group. To achieve a statistical power of 80% to detect an effect at α level of 5%, at least 161 patients were needed in each group. Continuous variables were expressed as mean ± SD and categorical variables as percentage. Continuous variables were compared with Student’s t-test for normally distributed variables; nonparametric variables were tested with Mann-Whitney’s U-test. Normality was tested with means of Q-Q plots. The correlations between variables were tested with Pearson’s bivariate correlation test, Chi square test and Student’s t-test. Variables above the threshold p value of 0.1 were included for multivariate analysis. The Cox regression model was used for primary analysis and included covariates that had a p value of more than 0.1 in univariate analysis. Estimates of treatment effect were expressed as hazard ratios with 95% confidence interval. Kaplan-Meier curves were constructed to determine time-to-event end-points. Differences in survivals between groups were determined with the Log-rank and Breslow tests. P value of > 0.05 was selected as the level of significance. All statistical analyses were performed on SPSS for Windows 10 v. 22 (IBM).

Continuous variables were expressed as mean ± standard deviation (SD) and categorical variables as percentage. Continuous variables were compared with Student’s t-test for normally distributed variables; nonparametric variables were tested with Mann-Whitney’s U-test. The cut-off levels of continuous variables were determined by means of receiver operator curves with cut-off value of AUC above 0.75 and p value of less than 0.05. Variables above the threshold p value of 0.1 were included for multivariate analysis. The Cox regression model was used for primary analysis. Estimates of treatment effect were expressed as hazard ratios with 95% confidence interval. Kaplan-Meier curves were constructed to determine time-to-event endpoints. Differences in survivals between groups were determined with the Log-rank and Breslow tests. P value of >0.05 was selected as the level of significance. All statistical analyses were performed on SPSS for Windows 10 v. 22 (IBM).