Spss software version

Statistical analyses were performed using the SPSS software version 25. Shapiro–Wilk test was used to assess normal distribution. Normally distributed variables were expressed as mean ± standard deviation (SD). Median and interquartile range (IQR) were calculated for non‐normally distributed variables. Spearman's correlation analysis was applied to assess the correlation between PTT and PSG variables. Changes in PTT and PSG variables before and during CPAP therapy were assessed via paired samples t tests.

Statistical analyses were performed using the SPSS software version 21. Visual and analytical methods were used to investigate whether the variables were normally distributed. Median and minimum-maximum values were used to present non-normally distributed variables. The Wilcoxon test was used to compare the change in scores between the pre-test and post-test analysis. A p value of less than 0.05 was considered to show a statistically significant result.

All experiments were carried out in triplicate. All values were expressed as the mean ± SEM. Statistical analysis was performed using the SPSS software (version 24.0, SPSS Inc., Chicago, IL, USA) by either an independent Student’s t-test or one-way analysis of variance (ANOVA) with Tuckey post hoc analysis. For all analyses, p < 0.05 is indicated as a statistically significant.

Statistical analysis was performed using SPSS software version 18 and two-sided P-value 0.05 (two-tailed) was considered statistically significant. We used the Wilcoxon rank-sum test to compare promoter methylation levels of HNSCC tumor samples and normal samples, which permit the comparison of two groups of independent samples [43 (link)]. The significant values were further adjusted for multiple testing by Bonferroni method (P-value multiplied by number of comparisons). Also, to strengthen the association between different factors and CIMP in HNSCC risk, P-values were calculated after adjusting confounding factors such as age, gender, HPV, smoking, betel-quid and tobacco chewing status as appropriate. Test for linear trend was also carried for multiple ordinal CIMP status. Unsupervised hierarchical clustering was done using JMP 12 software package of SAS, which identify subgroups among HNSCC patients based on promoter methylation frequency.