Figure 3:Application of the PCA models with different bucket widths for the classification of the test-set samples. Healthy subject samples are colored blue, dark blue indicates that the sample was classified within the confidence interval, light blue outside. Infected subject samples are colored green, dark green indicates that the sample was classified within the confidence interval, light green outside. The different models improve in classification with decreasing bucket width, 0.01 ppm performing best. Only one infected subjected sample is classified wrongly, but it also is identified as out of the confidence interval for the model.