DEFINITION: In statistics, an outlier is an observation that is
numerically distant from the rest of the data.
How to calculate an outlier
1) Subtract the lower quartile from the higher quartile
to get the interquartile range, IQ.
2) Multiply the interquartile range by 1.5. Add this to
the upper quartile and subtract it from the lower
quartile. Any data point outside these values is an
outlier.
The lower fence is the lower cut-off point for outliers
The upper fence is the upper cut-off point for outliers
Lower Fence = Q1 - 1.5(IQ)
Upper Fence = Q3 + 1.5(IQ)