title: [Application of factor analysis in comprehensive evaluation of semen quality].
abstract: OBJECTIVE
  To explore the application of factor analysis in comprehensive evaluation of semen quality.
  
  
  METHODS
  Using factor analysis, we examined the semen samples from normal fertile men and comprehensively evaluated their quality by extracting typical common factors from the sperm parameters, such as semen volume, sperm concentration, total number of sperm, total motility, progressive motility, vitality, sperm morphology, total number of progressive motile sperm, total number of valid progressive motile sperm, teratozoospermia index (TZI), sperm deformity index (SDI), curvilinear velocity (VCL), straight-line velocity (VSL), average path velocity (VAP), amplitude of lateral head displacement (ALH), linearity (LIN), wobble (WOB), straightness (STR), beat-cross frequency (BCF) and mean angular displacement (MAD).
  
  
  RESULTS
  Based on the principle of the cumulative variance contribution rate of 85% or more, we extracted 6 common factors with the cumulative variance contribution rate of 86. 647%, which in sequence represented sperm count, velocity, direction of movement, deformity index, semen volume and normal sperm morphology. The composite factor scores were calculated by the formula of (36.243 * F1 + 23.342 * F2 + 8.910 * F3 + 8.500 * F4 + 5.538 * F5 +4.115 * F6)/ 86.647, with a median of -0.0180. With the 5th percentile as the lower reference limit, 95.1% of the fertile males met the WHO limit for composite factor scores, while only 79.2% of them met the limit for semen parameters (P = 0. 000).
  
  
  CONCLUSIONS
  Compared with the routine detection of sperm parameters, factor analysis or composite factor scores could give a more accurate comprehensive evaluation of semen quality.
authors.affiliation: Section of Epidemiological Suvery and Research, Family Planning Hospital of Guangdong Province, Guangzhou, Guangdong 510600, China. wangqiling2006@126.com
authors.forename: Qi-Ling
authors.initials: QL
authors.lastname: Wang
mesh_terms: D005163:Factor Analysis, Statistical; D006801:Humans; D008297:Male; D055101:Semen Analysis; D013076:Sperm Count; D013081:Sperm Motility