A data integration and analysis system configured to gather detection data that are detected by sensors for detecting the operation statuses of controlled devices mounted on a plurality of railway vehicles, and further configured to extract measures for improving the performances of the railway vehicles from the detection data, wherein each of the plurality of railway vehicles includes a vehicle data analysis processing unit configured to perform correlation analysis between a plurality of desired indexes that show the performance of each of the plurality of railway vehicles and a plurality of explanatory indexes that show the statuses of the controlled devices generated from the detection data, the desired indexes being set to the consumed electric energies of devices mounted on the relevant railway vehicle, the ride quality of the relevant railway vehicle, the reliability of the relevant railway vehicle, or a combination thereof, and the correlation analysis being performed by the vehicle data analysis processing unit every constant time interval, every constant traveling distance, or every traveling distance between any two adjacent railroad stations, wherein the data integration and analysis system includes a data central analysis apparatus configured to gather the correlation analysis result from the vehicle data analysis processing unit included in each of the plurality of railway vehicles and extract explanatory indexes that have the highest correlations with the desired indexes on the basis of the plurality of correlation analysis results, and wherein the data central analysis apparatus is configured to feed the extracted explanatory indexes back to the railway vehicles as the measures for improving the performances of the railway vehicles. wherein each of the plurality of railway vehicles includes a vehicle data analysis processing unit configured to perform correlation analysis between a plurality of desired indexes that show the performance of each of the plurality of railway vehicles and a plurality of explanatory indexes that show the statuses of the controlled devices generated from the detection data, the desired indexes being set to the consumed electric energies of devices mounted on the relevant railway vehicle, the ride quality of the relevant railway vehicle, the reliability of the relevant railway vehicle, or a combination thereof, and the correlation analysis being performed by the vehicle data analysis processing unit every constant time interval, every constant traveling distance, or every traveling distance between any two adjacent railroad stations, wherein the data integration and analysis system includes a data central analysis apparatus configured to gather the correlation analysis result from the vehicle data analysis processing unit included in each of the plurality of railway vehicles and extract explanatory indexes that have the highest correlations with the desired indexes on the basis of the plurality of correlation analysis results, and wherein the data central analysis apparatus is configured to feed the extracted explanatory indexes back to the railway vehicles as the measures for improving the performances of the railway vehicles.