# What is a good standard deviation in investing?

## What is a good standard deviation in investing?

Standard deviation allows a fund's performance swings to be captured into a single number. For most funds, future monthly returns will fall within one standard deviation of its average return 68% of the time and within two standard deviations 95% of the time.

σ

## What is the symbol of deviation?

Probability and statistics symbols table
SymbolSymbol NameMeaning / definition
var(X)variancevariance of random variable X
σ2variancevariance of population values
std(X)standard deviationstandard deviation of random variable X
σXstandard deviationstandard deviation value of random variable X

## What test is used to compare two means?

The compare means t-test is used to compare the mean of a variable in one group to the mean of the same variable in one, or more, other groups. The null hypothesis for the difference between the groups in the population is set to zero. We test this hypothesis using sample data.