identifying outliers with standard deviation here' histogram of the actual data we were looking at in the preceding example for calculating variance now we see that the number occurred twice in our datasetand then we had one one and one the standard deviation is usually used as way to think about how to identify outliers in your dataset if say if ' within one standard deviation of the mean of that' considered to be kind of typical value in normal distribution howeveryou can see in the preceding diagramthat the numbers and actually lie outside of that range so if take plus or minus we end up around and and and both fall outside of that range of standard deviation so we can say mathematicallythat and are outliers we don' have to guess and eyeball it now there is still judgment call as to what you consider an outlier in terms of how many standard deviations data point is from the mean you can generally talk about how much of an outlier data point is by how many standard deviations (or sometimes how many-sigmasfrom the mean it is so that' something you'll see standard deviation used for in the real world