Question: understanding the meaning boxplot
gravatar for farahqureshi5
20 months ago by
farahqureshi50 wrote:


can anyone tell me how to understand the contents of boxplot. what does it indicate

ADD COMMENTlink modified 20 months ago by Peter Langfelder1.6k • written 20 months ago by farahqureshi50

Bioconductor isn't the right place to ask questions about elementary statistical methods. However Google is your friend and it will surely tell you all you need to know.

ADD REPLYlink modified 20 months ago • written 20 months ago by Gordon Smyth35k
gravatar for Peter Langfelder
20 months ago by
United States
Peter Langfelder1.6k wrote:

From help(boxplot.stats):


    The two ‘hinges’ are versions of the first and third quartile,
     i.e., close to ‘quantile(x, c(1,3)/4)’.  The hinges equal the
     quartiles for odd n (where ‘n <- length(x)’) and differ for even
     n.  Whereas the quartiles only equal observations for ‘n %% 4 ==
     1’ (n = 1 mod 4), the hinges do so _additionally_ for ‘n %% 4 ==
     2’ (n = 2 mod 4), and are in the middle of two observations

     The notches (if requested) extend to ‘+/-1.58 IQR/sqrt(n)’.  This
     seems to be based on the same calculations as the formula with
     1.57 in Chambers _et al_ (1983, p. 62), given in McGill _et al_
     (1978, p. 16).  They are based on asymptotic normality of the
     median and roughly equal sample sizes for the two medians being
     compared, and are said to be rather insensitive to the underlying
     distributions of the samples.  The idea appears to be to give
     roughly a 95% confidence interval for the difference in two


ADD COMMENTlink written 20 months ago by Peter Langfelder1.6k
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