Table 1 

Analytical Parameters 

Before polishing data 
After polishing data 



Range, median CVs for 66 variables 
2–54% 
2–36% 
Range, mean CVs for 66 variables 
2–58% 
3–39% 
Median CV for all 66 variables 
12% 
12% 
Mean CV for all 66 variables 
19% 
17% 
By 13 Pairs, overall median CV 
9% 
9% 


"Before polishing data", primary (raw) analysis; "After polishing data", final analysis after manual reinspection (see text). The most critical data are the median coefficients of variation (CV); our median CV was ~10%, well within the levels necessary to conduct the proposed study. We also note that upon reexamination of the dataset for quality control purposes, 1% (11 peaks) was left unscored due to analytical concerns, and 3% (25 peaks) had scores that differed by >10% from the original call. These data suggest that, even in the absence of any optimization, we can consistently measure >96% of all metabolites with a median ± 10% precision. For the last line "By 13 pairs", we first determined the median CV for all 66 variables in each of the pairs, and then determined the mean/median of these values. By definition, overall mean CVs are unchanged by this difference in calculation procedure, and are not shown. 

Shurubor et al. BMC Clinical Pathology 2007 7:9 doi:10.1186/1472689079 