Figure 2.

Covariance and correlation between 1H NMR one dimensional urine spectra, and population characteristics. The color code (R2) corresponds to the correlation coefficients of the variables with each of the characteristics: A, ln(U-Cd); B, age; C, sex; D, ln(U-NAG); and E, smoking status. N = 127. α - The direction and magnitude of the signals relate to the covariation of the metabolites with sex in the model, that is, female (positive) and male (negative). β - Smoking status was classified into two classes. 1 = never smoked (negative), 2 = current smoker (positive). 3-HV, 3-hydroxyisovalerate; DMG, dimethylglycine; 4-DEA, 4-deoxyerythronic acid. Spectra that exhibited signs of bacterial contamination, analgesics or ethanol were excluded from these analyses [See additional file 1 Table S2].

Ellis et al. BMC Medicine 2012 10:61   doi:10.1186/1741-7015-10-61
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