Final answer:
The two common changes in accounting principles linked with accounting estimates are changes in depreciation method and adjustments to the allowance for doubtful accounts.
Step-by-step explanation:
The question pertains to the field of accounting and asks about the two most common changes in accounting principles that are closely associated with accounting estimates. These are typically changes in depreciation method and adjustments related to allowance for doubtful accounts. When a company decides to change its method of calculating depreciation, it may affect the estimated useful life or salvage value of an asset, hence altering the associated accounting estimates. Similarly, changes in the estimation of bad debts, which affect the allowance for doubtful accounts, would reflect a shift in the company's view of the collectability of its receivables. Both of these changes require companies to recalculate their financial statements to reflect these new estimates and disclose the effects of the changes in their financial reports.