Transcript Outlier - Mr. Joselson

Outlier
A convenient definition (for use in
our class)
• An outlier is a point which is 2 or
more times the range of any other
two data points. The outlier(s) will
be at the beginning or end of a list
of data.
Outliers can also occur when comparing relationships between two sets
of data. These outliers can be easily identified on a scatter diagram.
It is often best to discard outliers before determining the line of best fit.
More technical definition that you do NOT
need to know.
An outlier is an observation that lies an
abnormal distance from other values in a
random sample from a population. In a sense,
this definition leaves it up to the analyst (or a
consensus process) to decide what will be
considered abnormal.
A common definition is any point outside the
quartile 1 to quartile 3 that is more than 1.5
times the interquartile difference.