by , 4:10 PM EDT, October 20th, 2008

Apple is set to report its FY Q4 earnings on Tuesday. In the past, Apple has typically guided conservatively for the next quarter, hoping to beat the Street's estimates. This time, however, the task may be trickier given the state of the economy, and so Piper Jaffray's Gene Munster has provided some historical charts to assist with the assessment of Apple guidance for FY09 Q1.

Mr. Munster went back eight quarters and noted that during that time, Apple has guided on its earnings per share (EPS) about 9 percent below the expectations of the Street and 4 percent below on revenue. Then, when the actual earnings are reported, Apple blows away the EPS estimate by 27 percent and the revenue by 4 percent.

Source: Piper Jaffray

This time around, Mr. Munster predicts that Apple's guidance will be more conservative than usual. The problem is that if Apple guides too low, its stock will take a hit in the near term by investors who continue to be nervous about the economy. If Apple guides too high and doesn't meet expectations, the stock will take a similar hit in January.

Further complicating Apple's task is the fact that most of Apple's phenomenal Mac sales have occurred in July, August and early September, before the recent banking crisis surfaced. So no matter what Apple reports in terms of Mac sales, investors could be skeptical if Apple can maintain the pace. All eyes will be on Apple to see how they address that issue on Tuesday.

Mr. Munster expects Apple to report 2.8 million Macs sold, 11 million iPods, 5 million iPhones, revenue of US$11.42B and and EPS of $1.76. Despite everything that has happened with the stock market as a whole lately, he is holding to his target of $250 per share.

In afternoon trading, AAPL was at US$97.75, up $0.18 for the day.