Math Is Fun Forum

mbstats

Guest

normal distribution "Q" notation

hello, can someone tell me what the "Q"s in this image are supposed to be?

http://www.microbiologybytes.com/maths/graphics/distgraph.gif

thanks

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: normal distribution "Q" notation

hi mbstats,

These are called the lower quartile and the upper quartile.  25% of the values are below the LQ, then 25% up to the median, then 25% between that and the UQ and finally, 25% above that.

Some people use the interquartile range  (UQ - LQ) as a measure of spread.  Because it leaves out untypical high and low values, it gives a clearer representation of spread than the range (top value - bottom value).

Bob

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