These changes in lifetimes may arise both from changes in the frequency spectrum and in the strength of the anharmonic interactions between modes, which we return to later in the discussion. -Page 16 - The differing impacts on the 𝜅 latt 𝜏 CRTA ⁄ and 𝜏 CRTA combine to produce the trend in 𝜅 latt discussed above. In HeCo8Sb24, the ~4-5 % reduction in both parameters combine to reduce the 𝜅 latt by 8-9 % compared to pristine CoSb3. In ArCo8Sb24, the 𝜅 latt 𝜏 CRTA ⁄ are reduced by a larger 8-9 % but the 𝜏 CRTA are mostly unchanged, resulting in a 𝜅 latt higher than HeCo8Sb24 but lower than pristine CoSb3. Filling with Ne and Kr reduces the 𝜅 latt 𝜏 CRTA ⁄ by ~11-12 % while changing the 𝜏 CRTA by 0.5-1 %, producing a similar overall 𝜅 latt .