The analyst arrived at his new 8-million figure by looking at the typical percentage of iPods shipped in past June quarters and measuring the sequential and year-over-year growth rates. He then averaged the two estimates from his sequential and year-over-year growth numbers and came up with 8.9 million iPods for the quarter.
In the previous quarters, however, Munster has found that extrapolation of the first month data typically overshot the actual reported iPod unit number for the quarter, so he removed 10% from the initial unit estimate to arrive at 8 million.
The report claims that iPods have not been moving as fast as expected in April. However, this is likely to change with "Grads and Dads" buying in May and June likely to buoy iPod sales.