While the harmonic model provides a good approximation to the vibrational frequencies and modes of a material, it is incapable of predicting properties that arise from purely anharmonic effects such as thermal conductivity or the lattice expansion coefficient. There are multiple approaches to include these effects, ranging from third-order perturbative approaches to fully anharmonic molecular dynamics trajectories, with varying degrees of accuracy and computational cost. Quantifying the level of anharmonicity in a material is therefore necessary to ensure efficient calculations of these materials properties.