How Much Training Data is Required?

In Machine Learning Mastery.  Good place to start, but there is rarely a precise answer.  More is usually good.  A look at one of the most common questions to be asked of the analyst.  Or worse, not asked at all.  In today's world of having huge amounts of data, it still does not mean we have the data needed to ask the question at hand.   Or don't have the meta data to support the conclusion.  Or don't understand how the context in which the data was gathered changes the solution.