The lab report contains the theory, process, data and calculation of the experiment. The theory and process are remains fixed for a particular experiment. Thus there is no chance to get error from these two part. The calculation depends upon the reading or data of the experiment. The calculation is also unique and based on the data. Thus the error come from the data of the experiment. As for example for a titration experiment the data recorded in the process from the burret is the source of error, on which the calculation depends.