detailed description of the nature of our sales deductions and our procedures for estimating our obligations. For example:

• For Medicaid, Medicare and performance-based contract rebates, we use our experience ratio of rebates paid and actual prescriptions written during prior quarters, which may be adjusted to better match our current experience or our expected future experience.

• Outside the U.S., the majority of our pharmaceutical rebates, discounts and price reductions (collectively, sales allowances) are contractual or legislatively mandated and our estimates are based on actual invoiced sales within each period, which reduces the risk of variations in the estimation process. In certain European countries, rebates are calculated on the government’s total unbudgeted pharmaceutical spending or on specific product sales thresholds, and we apply an estimated allocation factor against our actual invoiced sales to project the expected level of reimbursement. We obtain third-party information that helps us monitor the adequacy of these accruals.

• For chargebacks, we closely approximate actual as we settle these deductions generally within two to five weeks after incurring the liability.

• For sales returns, we perform calculations in each market that incorporate the following, as appropriate: local returns policies and practices; returns as a percentage of sales; an understanding of the reasons for past returns; estimated shelf life by product; an estimate of the amount of time between shipment and return or lag time; and any other factors that could impact the estimate of future returns, such as loss of exclusivity, product recalls or a changing competitive environment.

• For sales incentives, we use our historical experience with similar incentives programs to predict customer behavior.

These deductions represent estimates of the related obligations and, as such, judgment and knowledge of market conditions and practice are required when estimating the impact of these sales deductions on gross sales for a reporting period. Historically, our adjustments to actual results have not been material to our overall business. On a quarterly basis, our adjustments to actual results generally have been less than 1% of biopharmaceutical net sales and can result in either a net increase or a net decrease in income. Product-specific rebate charges, however, can have a significant impact on year-over-year individual product growth trends. If any of our ratios, factors, assessments, experiences or judgments are not indicative or accurate predictors of our future experience, our results could be materially affected. The sensitivity of our estimates can vary by program, type of customer and geographic location. However, estimates associated with U.S. Medicaid and performance-based contract rebates are most at-risk for material adjustment because of the extensive time delay between the recording of the accrual and its ultimate settlement, an interval that can generally range up to one year. Because of this time lag, in any given quarter, our adjustments to actual can incorporate revisions of several prior quarters.

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