When we make a graph for the determination of density, we place the mass on the y-axis and the volume on the x-axis, then plot each point. The greater accuracy achieved in the graphical method lies in the fact that a line of best fit is drawn to accommodate every point that is present on the graph. This means that all of the readings are being used to calculate the density; whereas, if you were to calculate density using only one reading of mass and volume, it would be far less accurate because it uses less data.