Necessary Sample Size = (Z-score) 2 * StdDev*(1-StdDev) / (margin of error) 2
95% confidence interval (Z-score = 1.96), Standard Deviation (StdDev = 0.5) and margin of error = ± 3.8 or 5 %. Therefore, our sample size adjustment was between 400 and 700 respondents.
All statistical analyses were carried out using the Statistical Package for Social Sciences Software (SPSS) version 20.01 (IBM Corporation, Armonk, NY, USA). The results were presented as means, frequencies and tables. The confidence interval was 95% and considered statistically significant at P < 0.05. Statistical analysis was performed for age, educational background, occupation, religion, gestational age, awareness and acceptance of epidural labour analgesia and reasons for unwillingness to accept epidural labour analgesia using one-way ANOVA, multiple comparisons by Tukey’s test and logistic regression. The student’s t-test was used for statistical comparisons between two groups.