One of the most fashionable research pursuits of our time, in the mathematical sciences, is Big Data Science. Fashionable pursuits attract a great deal of interest and funding, which creates more interest and funding, so that fashionable pursuits can quickly dominate research effort.
In 1899, more than a century ago, Karl Pearson, Alice Lee, and Leslie Bramley-Moore discovered an interesting phenomenon, in wihch it was found that a statistical association between two different groups was reversed when the groups were combined.
In my last column, I introduced a technique of proof known as "mathematical induction". It is a powerful technique, aimed at proving general formulas, by showing that each instance of the formula implies the truth of the next.
Q1441. Hundreds of millions of pebbles were deposited on the foreshore of a beach. Every high tide, 20% of the pebbles are transported from the deep end to the shallow end.