You can claim that a reduction in sales is because of a supply shortage, but the only way to prove it is to remove that constraint.
According to NPD data cited by Piper Jaffray analyst Gene Munster, Mac sales rose 31 percent year over year for the month of January. Why? Simple. Said Munster, “We believe the reason for the significant improvement in the sales data is primarily due to Apple catching up with iMac supply.”
Of course, this begs the question, why is Apple, currently being led by what many people would describe as an “Ops Guy”, running in to supply constraints?