Variance In A Nutshell
Variance can also be looked at in the same breath as volatility, because you can determine when the data point should be moving in relation to the complete data set and mean. This tool is important in technical analysis because you can see where the chart should be and how variance is affecting the movement. You can also use this fundamentally to determine if the numbers are in line or are they becoming an outlier.
Using as much data as you can may not be the best, so rather you should find a few that help narrow your decision making progress. Variance is the spread or difference between the data points in your chosen data set. You could look at variance if you are looking for the probability of a distribution happening. In investing and trading, you want to give yourself the best possible edge and increasing the probability of profitability.
Closer Look at Variance
If you are a long term investor, you want to use variance with other correlations to help you determine the optimum levels of risk and volatility. Of course you have to determine all of the data points, and with tools such as excel, it can make the job slightly easier. Many managers and fund managers do this already and have powerful tools to provide you with answers.
Some technical tools you can use this with are Bollinger Bands, which can give you an idea of where the chart may want to be. Also, using momentum indicators can give you an edge to see if the chart is over bought or sold. As with anything, these are not one hundred percent and should be molded to your current investing and trading styles. Statistics are great because they give you hard data points and can help in probability trading.
Some of the downfalls could be it eliminates the human element such as market fear and market chatter. As much as there is for statistics and data, there will always be a human element that needs to be accounted for. Sure, it may pick up on the movements relative to data, but that is not the true market emotions. Also, variance may not work with your current situation, causing all of this data to be irrelevant.
All in all, find what works best for you and go from there. You may find out that this works or only part of it works. Take the time to study variance and know it inside and out. If you get stuck, reach out to an investing community and bounce your ideas off of them, as they can help to guide your thoughts and ideas.