[Response] Thanks for your comments. We have revised it in the Manuscript. Line 255-257.
33. How does the author know that these errors are low enough? How do they compare to the standard deviation of the reference values of TPC, TGP, THP, OTG, AV and PV? Could these errors be simply a reflection of the standard deviations of each index?
[Response] The Mean Square Error (MSE) lower than 1 in the model indicated excellent classification performance and prediction ability (Cavanna, Righetti, Elliott, & Suman, 2018). The MSE is different from the standard deviation (SD) of each index, the MSE is the square root of the ratio of the sum of the squares of the deviation between the observation value and the true value to the number of observations. It is used to measure the deviation between the observed value and the true value.