Recently I was privileged to sit on the committee that selects the winner of the Karl Pearson Prize. KP was, of course, an early mathematical statistician, famous for many commonly-used statistical methods and tools including histograms, the correlation coefficient, the method of moments, p-values, the chi-squared test and principal components analysis. He is also infamous for his highly racist views, support for eugenics, anti-semitism and for refusing a knighthood. All that aside, the job of the committee was to select an English-language article or book published in the last 30 years that has made a stand-alone research contribution, and which has had major influence on one or more of statistical theory, statistical methodology, statistical practice and application. There were many excellent nominations, but we decided to award the 2017 prize to Rod Little and Don Rubin for their 1987 book "Statistical analysis with missing data".