Statistics -Skewness and kurtosis

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Mr. Saad
Skewness and Kurtosis

2. Skewness:
 Any depart from the symmetrical distribution is
called skewed distribution
 Lack of symmetry in a distribution around some
central value is called skewness or
asymmetrical.
 If the longer tail is on the right side the distribution
is called positively skewed distribution and in
case of positive skewness Mean>Median>Mode.
 If the longer tail is on the left side, the distribution
is called negatively skewed and in case of
negative skewness Mean<Median<Mode
 A distribution is called symmetrical or normal if
the frequency curve has the same shape on both
sides of the line which divide the curve in two
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3. Normally distributed Curve
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4. Positively Skewed
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5. Negatively Skewed
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6. Kurtosis:
 Peakness or Length of Data
 Kurtosis is the degree of peakness of a
distribution usually taken relative to normal
distribution.
 Used to find degree of peakness of distribution
 There are three types of Peakness.:
 Lepto-Kurtic: (curve which is tall and lean at the
top is called Lepto-Kurtic)
 Meso-Kurtic: (curve with moderate peak is call
normal or Meso-Kurtic)
 Playto-Kurtic: (curve which is flat like a plate at
the top is called Playto-Kurtic)
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7. Types:
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