2.5. Statistics
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SPSS software (version 18.0) was used for data analysis. The measurement data that conformed to the normal distribution are expressed as the mean ± standard deviation (x̅ ± s), and the differences between the 2 groups were compared using an independent sample t-test. Differences among the 3 groups were compared using one-way analysis of variance. Count data, expressed as percentages (%), were analyzed using the chi-squared (χ