3.3 Statistical analysis
Statistical methods were used to analyse the scores of volunteers in the SSOI, MD-OI, and CMOI tests. After the paired sample Friedman M test, the average values of the three groups were not the same (P = 2.6757e-26 < 0.0001), and the scores of volunteers in the MDOI test were significantly higher than those in the SSOI test (P = 8.5854e-12 < 0.001). The scores of volunteers in the CMOI test were significantly higher than those in the MDOI test (P = 8.6864e-13 < 0.0001) and SSOI test (P = 8.6864e-13 < 0.0001). The co-rrect recognition rates of odors in the SSOI and CMOI tests were tested by the Wilcoxon signed-rank sum test of paired samples. The correct recognition rates of test odors in the CMOI test were significantly higher than that in the SSOI test (P = 0.006 < 0.05).