Patent ID: 7191037

Claim:
A method for controlling a production process without having to resort to the preparation of a calibration curve for predicting data for analysis samples, the method comprising taking an absorbance spectrum for each of a plurality of standard samples collected from a production process step in an analysis range including near-infrared region, constructing a data base from a differentiation curve of a near-infrared spectrum chart obtained using a plurality of production products that had been judged by conventional chemical analysis to be rated products, by calculating standard deviations and the average intensity of the standard samples (standard average intensity) in respect of each of the wave lengths selected from the spectrum included in the said analysis range at a constant interval, taking an absorbance spectrum in the said analysis range for each analysis sample collected from the production process step and comparing the resulting absorbance spectrum with the data base, estimating the deviation (analysis deviation) of the intensity of the absorbance spectrum of each of the analysis samples (analysis intensity) at each of the said selected wave lengths from the standard average intensity, comparing, when the absorbance spectrum includes wave length(s) at which the analysis deviation of the absorbance of the analysis sample is outside a tolerance limit determined based on the standard deviation, the wave length showing the analysis deviation of the absorbance outside the tolerance limit with production information given preliminarily in the data base in order to find out one or more control factors responsive to said analysis deviation of absorbance of the analysis sample, estimating control data for reclaiming the production process based on the one or more control factors, and controlling the production process so as to obtain production product within the said tolerance limit by inputting the said control data to the production process step.