Colour-shift point of indicator and titration error for complexation titration

The theoretical colour shift point of indicators is different from the end point of titration .The titration error of Bi 3+ ,Zn 2+ ,Pb 2+ ,Cd 2+ ,Ca 2+ and Mg 2+ was calculated ,and then compared with the data obtained from literature .So,the mistake,which exists for a long time,of using theoretical colour shift point as end point of titration was rectified.