Back in 1974, Yale poli-sci professor Edward Tufte published a slim volume called Data Analysis for Politics and Policy (Prentice-Hall, $3.95). The book in its entirety is available for free download (PDFs) at Tufte's website, accompanied by a contemporary review from the Journal of the American Statistical Association. More than 30 years later, the review amuses me with its restrained praise of the perspective that would eventually make Tufte a Major Figure (and a minor fortune): Tufte puts residual plots to good use to gain understanding of a data set, and he shows how finding outliers gives the analyst hints about the inadequacy of a statistical model... The discussion of graphical techniques in general is quite good... A brief but compelling discussion of the "value of data as evidence," with regard to the interpretation of nonrandom samples, is presented. If you happen to have a spare 48MB lying about, DAPP's worth a download.