"Figures often beguile me, particularly when I have the arranging of them myself; in which case the remark attributed to Disraeli would often apply with justice and force: 'There are three kinds of lies: lies, damned lies and statistics.'"
- Autobiography of Mark Twain
I first learned this lesson my sophomore year of high school in beginning Debate, when the topic was Homelessness. Every advocacy group and most media outlets repeated, citing multiple sources with authority, that there were about 3 million homeless people in the United States. But when you did a little research and drilled down, every single one of those sources derived from just one person - a homeless advocate named Mitch Snyder who testified before Congress in 1982 the results of a study that was later discredited. He later admitted to fully making the number up out of whole cloth. The 1990 census, the first to do a full scale "find 'em and count 'em" study, could only find about 250,000. Still a problem, but 1/12 of the problem advocates claimed. Of course, that was far more about attacking Ronald Reagan than addressing the homeless issue, but then, that's no surprise to anyone.
No one who claims to be serious about trying to responsibly prioritize and address society's problems with other people's money can do so without understanding how organizations from scientists to NGOs to PACs to governmental departments themselves warp their data to support their preconceived notions. One of the few valuable things I learned while getting my political science degree was how polls work and how they don't work, and how questions can be skillfully asked and the pool carefully chosen to arrive at The People's ("correct") Opinion.
We see it all the time in global warming scares, economic statistics, polls, Jihadist propaganda, military stories, education studies demanding more money, affirmative action stories, race relations, etc. It colors everything we read.
To that end, Thomas Sowell recently published a three part must read on how pervasive the problem is, and how important it is to truly understand any news article from any source. (Part I | Part II | Part III)
Drilling skepticism is crucial to good science (which is why global warming is not), good legal reading and writing, good journalism, and most importantly, good citizenship.