As part of an experiment, I'm verifying the existence of a linear relationship between curvature and bending moments for three beams using different materials. The plotted data can be seen below. Visually, there is a very strong positive linear relationship. Visually, the residuals are small. Of the three populations of data, the lowest Pearson coefficient is 0.9998, the highest is 0.9999.
In terms of verifying this linear relationship in a lab report, need I discuss anything other than the regression lines being visually straight and the residuals being visually small? Is it necessary to calculate the Pearson coefficients? Should any other statistical tests be carried out such as the coefficient of determination?