Mean Deviation vs. Downside Deviation

The mean deviation of the equity instrument is the first measure of the distances between each value of security historical prices and the mean. It gives us an idea of how spread out from the center the distribution of returns.

Mean Deviation

 = 

SUM(RET DEV)

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Mean Deviation is the average of the absolute values of the differences between price distribution numbers and their mean. Mean deviation of equity instrument with a lot of historical data is a biased estimator because the time horizon used in calculation will always be much smaller than the entire price history of the equity. The mean deviation is typically used as a measure of dispersion for small investment horizon, otherwise standard deviation is a better measure of dispersion.

Mean Deviation In A Nutshell

A way to implement this tool is if you’re investing and want to ensure you equity or product is not getting to far from the mean. If you notice the product is increasing and is way past the deviation levels, this could be an indication you may want to look at taking products. This tool could work for intra day trading as well, giving you areas to watch and take action if the product gets too out of line. 

Similar to standard deviation, this is a way to gauge how far a data point is from the mean or where is should be speaking in loose terms. The mean deviation is the mean of that data you are analyzing’s absolute deviations around the mean of your data, or the average distance from the mean. So, similar to standard deviation, it is telling you where the data should be and when to be alert that is has gone too far from the average or mean.

Closer Look at Mean Deviation

When using products such as this, it is important to fully understand what makes up the equation, that way you know how it works and can adjust it in the future. Sure, you may understand the data it puts out, but you may not know why it is what it is. That way, if a data point gets to far away, you can analyze why that is. Be sure to test this out on a demo account first, that way you understand how it functions and if it will be a good fit. If you ever have questions, reach out to an investing community and begin bouncing ideas off of others. That is the best way to learn how this is being used in the real financial world.