inflation, cost of capital, marketing spending, foreign currency exchange rates, tax rates and capital spending. These factors are even more difficult to predict when global financial markets are highly volatile. The estimates we use when assessing the recoverability of noncurrent assets are consistent with those we use in our internal planning. The estimates we use when performing impairment tests are management's best assumptions that a hypothetical marketplace participant would use. Management periodically evaluates and updates the estimates based on the conditions that influence these factors. The variability of these factors depends on a number of conditions, including uncertainty about future events, and thus our accounting estimates may change from period to period. If other assumptions and estimates had been used in the current period, impairment charges could have resulted. As mentioned above, these factors do not change in isolation; and therefore, it is not practicable to present the impact of changing a single factor. Furthermore, if management uses different assumptions or if different conditions occur in future periods, future impairment charges could result. 

Our Company faces many uncertainties and risks related to various economic, political and regulatory environments in the countries in which we operate, particularly in developing or emerging markets. Refer to the heading "Our Business—Challenges and Risks," above, and "Item 1A. Risk Factors" in Part I of this report. As a result, management must make numerous assumptions which involve a significant amount of judgment when completing recoverability and impairment tests of noncurrent assets in various regions around the world. 

We perform recoverability and impairment tests of noncurrent assets in accordance with accounting principles generally accepted in the United States. For certain assets, recoverability and/or impairment tests are required only when conditions exist that indicate the carrying value may not be recoverable. For other assets, impairment tests are required at least annually, or more frequently, if events or circumstances indicate that an asset may be impaired. 

Investments in Equity and Debt Securities 

The carrying values of our investments in equity securities are determined using the equity method or the cost method, or at fair value. Refer to the heading "Critical Accounting Policies and Estimates—Basis of Presentation and Consolidation," above. Our investments in debt securities are carried at either amortized cost or fair value. Investments in debt securities that the Company has the positive intent and ability to hold to maturity are carried at amortized cost and classified as held-to-maturity. Investments in debt securities that are not classified as held-to-maturity are carried at fair value, and classified as either trading or available-for-sale. 

Investments classified as trading securities are not assessed for impairment, since they are carried at fair value with the change in fair value included in net income. We review our investments in equity and debt securities that are accounted for using the equity method or cost method or that are