A competent analyst looking at a complex problem often is able to break things down into more manageable chunks. Some of these chunks are constants which can be skimmed over, while other components are highly variable and deserve an in-depth inquiry to figure out what is actually going on and what probable future scenarios could look like. Good analysts are then able to pull together a coherent story to tell their boss, to tell their clients, or to inform their own actions. This story incorporates the known realities and does not exclude unfavorable data.
State Department released its annual Country Reports on Terrorism showing a number of interesting findings, including steep declines in terrorist attacks and murders in many regions of the globe......
So if you exclude Iraq, he argues that Bush's strategy is successful as we only saw a global increase in fatalities by 14%. This 14% increase in fatalities is the good news that the guy is trying to sell.
On the other hand, a good analysis of the economy by Caroline Baum [h/t Barry at the Big Picture]uses component analysis to look at the impact of housing on the broader economy. The picture is not pretty but I just want to pull one great quote on the limitations of component analysis from her.
"Excluding housing, the U.S. economy is doing just fine.
Being able to exclude data to illustrate points, to find strengths and weaknesses and look for underlying trends is a good thing. However the best analysts remember that they made these exclusions and include this information when they actually think about their recommendations and descriptions of reality. Permanently excluding Iraq from any broad discussion of terrorism, national security or foreign policy instantly marks the analyst as incompetent.