In 2015, there was no consensus on the nature of this and other observed anomalies and their statistical significance is unclear. For example, a study that includes the Planck mission results shows how masking techniques could introduce errors that when taken into account can render several anomalies, including the axis of evil, not statistically significant. A 2016 study compared isotropic and anisotropic cosmological models against WMAP and Planck data and found no evidence for anisotropy.