Step 3 View Histograms of Selected Variables

The training set will be used to calculate the multivariate mean and variance-covariance matrix however, before calculating these parameters, we will graphically examine the training set to see if it contains measurements that are approximately normally distributed. This can be accomplished by several methods, the simplest being to plot histograms of the individual variables. Use the MATLAB hist command to 

FIGURE 3.10 Histogram showing the absorbance of the sulfamethoxazole training set at 2264 nm. 

4 Step 4 Compute the Training Set Mean and Variance-Covariance Matrix 

Correlation Coefficients between Absorbance at Selected Pairs of Wavelengths for Sulfamethoxazole Training Set 

FIGURE 3.11 Scatter plot of absorbance at 1912 nm vs. 2264 nm for the sulfamethoxazole training set. Ellipses are drawn at the 80 and 95% confidence intervals. 

---