Sales estimates are for sales since July 21, 2009, when our Blu-ray sales tracking started. Sales for The Dark Knight are therefore incomplete. All other titles have complete data. The release date is the date of the original release of the title on video.

Our DVD and Blu-ray sales estimates are based on weekly retail surveys, which we use to build a weekly market share estimate for each title we are tracking. The market share is converted into a weekly sales estimate based on industry reports on the overall size of the market, including reports published in Media Play News.

For example, if our weekly retail survey estimates that a particular title sold 1% of all units that week, and the industry reports sales of 1,500,000 units in total, we will estimate 15,000 units were sold of that title. The consumer spending estimate is based on the average sales price for the title in the retailers we survey.

We refine our estimates from week to week as more data becomes available. In particular, we adjust weekly sales figures for the quarter once the total market estimates are published by the Digital Entertainment Group. Figures will therefore fluctuate each week, and totals for individual titles can go up or down as we update our estimates.

Because sales figures are estimated based on sampling, they will be more accurate for higher-selling titles.