**0**wrote:

Greetings!!

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

**1.5k**• written 18 months ago by farahqureshi5 •

**0**

Question: understanding the meaning boxplot

0

farahqureshi5 • **0** wrote:

Greetings!!

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

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modified 18 months ago
by
Peter Langfelder • **1.5k**
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written
18 months ago by
farahqureshi5 • **0**

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Peter Langfelder • **1.5k** 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

otherwise.

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

medians.

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