Spss advanced statistics version 26

Questionnaire responses were assessed using descriptive statistics. Moreover, exercise intensity, changes in glucose levels over time, and the IAUC were determined using the Wilcoxon signed‐rank test. The IAUC was calculated using the trapezoidal method. SPSS Advanced Statistics Version 26 (IBM Japan, Ltd.) was used for all analyses. A P value of <.05 was considered statistically significant.

Statistical analyses were performed using IBM SPSS advanced statistics, version 26 (SPSS Inc., Chicago, Illinois, USA. Numerical data were presented as mean ± SD and median (range), whereas categorical data were presented as number (percent). The Mann-Whitney U-test and the χ²-test are used when appropriate. Statistical significance is considered if P value is less than or equal to 0.05.

Demographic results are expressed as mean±standard deviation (M±SD) and variables of performance and HRV as mean±the standard error of the mean (M±SEM). To compare variables with nap propensities between shorter and longer nap conditions, we used a Wilcoxon signed-rank test. Napping conditions (including the no-nap condition) were compared by using Friedman’s nonparametric analysis of variance. To assess differences of performance across sequential trials between napping conditions, linear mixed effect (LME) models were applied, as these enable effective use of all information, even that from participants with missing data, increasing the overall statistical power. LME allows the influence of factors for which data are extracted randomly from a population, providing more reliable results
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. To examine handball-related performance according to different napping opportunities, a model was built using “participant” as a random effect and “condition” (no nap, short nap, and long nap) as a fixed effect. Bonferroni correction for multiple comparisons was used during post-hoc analysis if the association was deemed significant.
Spearman's rank-order correlations were calculated to examine the association between task performance, PSQI, and the indices obtained by HRV analysis. All calculations were performed using (SPSS Advanced Statistics version 26, IBM Corp., Armonk, NY, USA).