Mark Jahn is a financial writer, editor, consultant, and award-winning economist covering ETFs, stocks, cryptocurrencies, options, and more. Somer G. Anderson is CPA, doctor of accounting, and an ...

In response to my article, Is the Stock Market Too Concentrated?, which relied upon standard-deviation calculations to assess investment risk, a reader wrote: “My problem [with your argument] is ...

WHEN a series of numbers can legitimately be regarded as random samples from a normal distribution, the mean range within small sub-groups, multiplied by a factor depending only on group-size, gives a ...