Moustache box
The box with moustache is average a rapid to appear the essential profile of a quantitative statistical series. She was invented in 1977 by John Tukey, but can be the subject of certain installations according to the users.
Principles
This diagram summarizes only some characteristics of position of the studied character (Médiane, Quartile S, minimum, maximum or Décile S). It is used mainly to compare the same character in two populations of different sizes. It is a question of tracing a going rectangle of the first quartile to the third quartile and half-compartment by the median. This rectangle is enough for the diagram out of box . One then adds segments at the ends carrying out up to the extreme values, or the first and ninth deciles (), even with 5th and 95e centiles. One speaks then about diagram out of moustache box or diagram with legs.Comparison of two diagrams out of moustache box with
- for the lower box: Q1 = 3, M = 7, Q3=12, ,
- for the higher box: Q1 = 7, M = 9, Q3=12, ,
History
In the diagrams out of box of Tukey, the length of the “moustache” is worth 1,5 times the interquartile variation. These diagrams of Tukey were used in sectors where the data can generally be modelled by using a normal Loi; in this case, the theory shows that the ends of the “moustache” are close to the first and 99e centile: these diagrams were especially used to detect the presence of exceptional data.The moustache boxes are currently in vogue in French teaching, since they belong to the programmes of mathematics in college and college. One also indicates them there under the term of boxes to legs like Box Stud .
See too
- Charts of statistical data
- very complete Document pdf
- Realization starting from Excel
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