There are various types of accounting changes, each of which is required to be reported differently.

Required:
1. What type of accounting change is a change from the sum-of-the-years'-digits method of depreciation to the straight-line method for previously recorded assets? Under what circumstances does this type of accounting change occur?
2. What type of accounting change is a change in the expected service life of an asset arising because of more experience with the asset? Under what circumstances does this type of accounting change occur?