outliers

[Chirpsy]

in box plots you can find outliers by finding the lower and upper fence. so i was just wondering if theres a method to finding outliers in scatterplots. or do you just identify outliers just by looking at it.
Also, in past exam assessment  reports, they sometimes use the term extreme values rather than outliers. so does that mean theyre the same thing or is there a distinct difference?
thanks

[Stick]

There's no concrete way of determining an outlier in a scatterplot. I guess you could find out the outliers in the x values and in the y values and then pinpoint data points which are outliers in both lists, but generally looking at the graph would be enough. Perhaps that is why the assessment report uses "extreme values" instead of "outliers" since it cannot be fully proven.