**Summary of observation**

In R, quartiles, minimum and maximum values can be easily obtained by the summary command

summary (x) x: data vector

It gives information on

- minimum
- maximum
- first quartile
- second quartile (median) and
- third quartile.

**Boxplot**

Boxplot is a graph which summarizes the distribution of a variable by using its median, quartiles, minimum and maximum values.

boxplot ( ) draws a box plot

**Descriptive Statistics:**

First hand tools which gives first hand information.

- Structure and shape of data tendency (symmetricity, skewness, kurtosis etc.)
- Relationship study (correlation coefficient, rank correlation, correlation ratio, regression etc.)

**Skewness**

Measures the shift of the hump of frequency curve.

Coefficient of skewness based on values x1,x2,....,xn.

**Kurtosis**

Measures the peakedness of the frequency curve.

Coefficient of kurtosis based on values x1,x2,...,xn.

**Skewness and Kurtosis**

First we need to install a package 'moments'

> install.packages ("moments")

> library (moments)

skewness ( ) : computes coefficient of skewness

kurtosis ( ) : computes coefficient of kurtosis

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