within two to five weeks of incurring the liability.

• Provisions for pharmaceutical returns are based on a calculation in each market that incorporates 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; and 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. In most markets, returned products are destroyed, and customers are refunded the sales price in the form of a credit.

• We record sales incentives as a reduction of revenues at the time the related revenues are recorded or when the incentive is offered, whichever is later. We estimate the cost of our sales incentives based on our historical experience with similar incentives programs.

Historically, our adjustments to actual have not been material; on a quarterly basis, they generally have been less than 1.0% of Biopharmaceutical net sales and can result in a net increase to income or a net decrease to income. The sensitivity of our estimates can vary by program, type of customer and geographic location. However, estimates associated with U.S. Medicaid and 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 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.

Collaborative Arrangements––Payments to and from our collaboration partners are presented in the statements of income based on the nature of the arrangement (including its contractual terms), the nature of the payments and applicable accounting guidance. Under co-promotion agreements, we record the amounts received from our partners as alliance revenues, a component of Revenues, when our co-promotion partners are the principal in the transaction and we receive a share of their net sales or profits. Alliance revenues are recorded when our co-promotion partners ship the product and title passes to their customers and the related expenses for selling and marketing these products are included in Selling, informational and administrative expenses. In collaborative arrangements where we manufacture a product for our partner, we record revenues when our partner sells the product and title passes to its customer. All royalty payments to collaboration partners are recorded as part of Cost of sales.

Long-Lived Assets

We review all of our long-lived assets, including goodwill and other intangible assets, for impairment indicators throughout the year and we perform detailed impairment testing for goodwill and indefinite-lived assets annually and for all other long-lived assets whenever impairment indicators are present. When necessary, we record charges for impairments of long-lived assets for the amount by which the present value of future cash flows, or some other fair value measure, is less than the