Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Andy Smith is a Certified Financial Planner ...

Reviewed by Eric Estevez Key Takeaways Standard error measures the accuracy of a sample mean by showing how much it deviates ...

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 ...

The normal distribution is the probability distribution that plots all of its values along a symmetrical bell curve, with the highest probabilities centered around the mean value and tapering out ...