tax rate, which seeks to incorporate the geographic diversity of the projected cash flows.

• The market approach is a historical approach to estimating fair value and relies primarily on external information. Within the market approach are two methods that we may use:

Guideline public company method—this method employs market multiples derived from market prices of stocks of companies that are engaged in the same or similar lines of business and that are actively traded on a free and open market and the application of the identified multiples to the corresponding measure of our reporting unit’s financial performance.

Guideline transaction method—this method relies on pricing multiples derived from transactions of significant interests in companies engaged in the same or similar lines of business and the application of the identified multiples to the corresponding measure of our reporting unit’s financial performance.

The market approach is only appropriate when the available external information is robust and deemed to be a reliable proxy for the specific reporting unit being valued; however, these assessments may prove to be incomplete or inaccurate. Some of the more significant estimates and assumptions inherent in this approach include: the selection of appropriate guideline companies and transactions and the determination of applicable premiums and discounts based on any differences in ownership percentages, ownership rights, business ownership forms or marketability between the reporting unit and the guideline companies and transactions.

Specifically:

• When we estimate the fair value of our four biopharmaceutical reporting units, we rely solely on the income approach. We use the income approach exclusively as the use of the comparable guideline company method is not practical or reliable. For the income approach, we use the discounted cash flow method.

• When we estimate the fair value of our Consumer Healthcare reporting unit, we use a combination of approaches and methods. We use the income approach and the market approach, which we weight equally in our analysis. We weight them equally as we have equal confidence in the appropriateness of the approaches for this reporting unit. For the income approach, we use the discounted cash flow method and for the market approach, we use both the guideline public company method and the guideline transaction method, which we weight equally to arrive at our market approach value.

Our Consumer Healthcare reporting unit has the narrowest difference between estimated fair value and estimated book value. However, we believe that it would take a significant negative change in the undiscounted cash flows, the discount rate and/or the market multiples in the consumer industry for the Consumer Healthcare reporting unit goodwill to be impaired. Our Consumer Healthcare reporting unit performance and consumer healthcare industry market multiples are highly correlated with the overall economy and our specific performance is also dependent on our and our competitors’ innovation and marketing effectiveness, and on regulatory developments affecting claims, formulations and ingredients of our