Confusion matrices for identifying EMP stars at different S/N levels. The top panels show the results with UV band spectra at S/N of 10, 20, and 30, while the bottom panels show them without UV band spectra. In each matrix, the upper left and lower right corners show the counts of correctly classified normal stars (label 0) and EMP stars (label 1), respectively. The lower left corner indicates the number of normal stars mistakenly classified as EMP stars (false positives), and the upper right corner represents EMP stars incorrectly identified as normal stars (false negatives). The intensity of the colour indicates the quantity, with darker colours representing higher numbers and lighter colours indicating lower numbers.