{smcl} {* 16 May 2004/16 June 2017}{...} {hline} help for {hi:extremes} {hline} {title:List extreme values of a variable} {p 8 17 2} {cmd:extremes} {it:numvar} [{it:other_vars}] [{cmd:if} {it:exp}] [{cmd:in} {it:range}] [ {cmd:,} {cmd:n(}{it:#}{cmd:)} {c -(} {cmdab:freq:uencies} {c |} {cmd:iqr}[{cmd:(}{it:#}{cmd:)}] {c )-} {cmdab:hi:gh} {cmdab:lo:w} {it:list_options} ] {p 4 4 2} {cmd:by} {it:...}{cmd::} may be used with {cmd:extremes}; see help {help by}. {title:Description} {p 4 4 2}{cmd:extremes} lists extreme values of {it:numvar}. If {it:other_vars} are also specified, these are also listed for the same observations. By default, the extremes are the 5 lowest and the 5 highest values of {it:numvar}. The option {cmd:n()} may be used to change 5 to any other integer. The option {cmd:iqr}, used with or without an argument, may be used to select extremes according to their distance from the nearer quartile. The option {cmd:frequencies} may be used to show the frequencies of distinct extreme values. Missing values are ignored. {title:Options} {p 4 8 2}{cmd:n(}{it:#}{cmd:)} specifies a number of values to be shown in each tail. {cmd:n} defaults to 5. {p 4 8 2}{cmd:frequencies} specifies that frequencies of distinct values be shown. That is, imagine the variable treated as discrete and shown as a histogram. The table shows the frequencies that would be shown as the {cmd:n} leftmost and/or the {cmd:n} rightmost bars of the histogram. {it:other_vars} may not be specified with this option. {p 4 8 2}{cmd:iqr} is short-hand for {cmd:iqr(1.5)}. See just below. {p 4 8 2}{cmd:iqr}{cmd:(}{it:#}{cmd:)} specifies use of a rule based on iqr (interquartile range) for identifying extremes. That is, calculate {p 16 16}(value - upper quartile ) / iqr {p 8 8 2}for any values at or above the upper quartile and {p 16 16}(value - lower quartile) / iqr {p 8 8 2}for any above at or below the lower quartile. Values will be shown if this ratio equals or exceeds {it:#} in absolute value. {cmd:iqr(1.5)} corresponds to a common rule for identifying individual points on box plots. {it:#} may be 0 or positive. {p 4 8 2}{cmd:frequencies} may not be combined with {cmd:iqr} or {cmd:iqr()}. {p 4 8 2}{cmd:high} specifies that only high values should be shown. {p 4 8 2}{cmd:low} specifies that only low values should be shown. {p 4 8 2}{it:list_options} are options of {help list} other than {cmd:noobs} and {cmd:subvarname}. {title:Examples} {p 4 8 2}{cmd:. sysuse auto, clear} {p 4 8 2}{cmd:. extremes price make} {p 4 8 2}{cmd:. extremes price make, iqr} {p 4 8 2}{cmd:. extremes price make, iqr(3)} {p 4 8 2}{cmd:. bysort foreign: extremes price make, iqr} {title:Author} {p 4 4 2}Nicholas J. Cox, University of Durham, U.K.{break} n.j.cox@durham.ac.uk {title:Acknowledgments} {p 4 4 2}This program owes a debt to Michael N. Mitchell's {cmd:hilo}. A problem posed by Sylvain Friederich led to tabulation by frequencies. David Puddicombe reported a bug. {title:Also see} {p 4 13 2}On-line: help for {help list}, {help hilo} (if installed), {help adjacent} (if installed)