Those in the know suggest the album, due out June 18, may sell 500,000 copies in its first week. Readers might wonder: How do said forecasters come up with a projected sales figure -- when the album isn't even on sale yet?
Basically, these skilled sources make it their business to crunch numbers all day long. Sales forecasts, such as this one for "Yeezus," are based on early orders from retailers, first-week performance of comparable albums, media exposure, radio and YouTube trends for an album's first single, and so forth. These sources each have their own forecast model, so to speak, that helps generate sales projections.
Sometimes, depending on how far out we are from an album's release, a forecast can be wildly different from the final outcome. In general, you can best guess an album's debut sales week once it's actually on sale.