A study conducted in industrial conditions was based on the principle of uncontrolled (passive) experiment, in which the distinct values of the occupational factors could not be set by investigator. Operators spend most of their time (80-90%) at their workplace and contact with the occupational factors, so the initial data for the statistic dependences were obtained by discrete simultaneous registration of changes in the entering factors and by taking into account the exposure time and corresponding changes in physiologic parameters. Since a physiologic curve of changes in the capacity for work during the shift has peaks and slumps, the initial data were divided into two patterns--before and after the dinner break. Manifold correlation analysis and following calculation of each factor's percentage in the total dispersion revealed the main occupational factors influencing the operator's health status, the percentage of each factor. The study brought about the regression equation to evaluate and forecast the strain during the work.