For years, Apple demolished its earnings forecasts. It would set comically low revenue guidance then deliver results that were significantly better.
This seems to have been a Steve Jobs idea. Because around the time Tim Cook took over, Apple revenue beats came back to earth.
In the first fiscal quarter of 2013, Apple changed its guidance and started providing a revenue range. Apple's CFO explained the change at the time saying, "In the past we provided a single point estimate that was conservative. This quarter and going forward, we are going to provide a range of guidance that we're likely to report within."
In the last three quarters, Apple's revenue guidance at the high-end of its forecast has been accurate within a 1% range. That means that when it reports earnings tomorrow, Apple should deliver ~$44 billion in revenue, give or take a percent.
