📐 Measure of Shape

Last Updated: Jan 2026


Measure of Shape describes the shape of data distribution.

It tells us:

  • Data kis taraf jhuk raha hai (skewness)
  • Data kitna peaked ya flat hai (kurtosis)

🗣 Hinglish Tip: Shape = data ka overall pattern / curve ka nature

Shape helps to:

  • Understand data distribution
  • Choose correct statistical methods
  • Analyze real-world datasets

Types of Measure of Shape

  1. Skewness
  2. Kurtosis

Skewness

Skewness measures the asymmetry of data distribution.

It shows whether data is:

  • Symmetric
  • Right-skewed
  • Left-skewed

Formula For Population Skewness

γ1=(xiμ)3Nσ3\gamma_1 = \frac{\sum (x_i - \mu)^3}{N\sigma^3}

Where:

  • γ1\gamma_1 = population skewness
  • μ\mu = population mean
  • σ\sigma = population standard deviation
  • NN = population size

Sample Skewness

g1=(xixˉ)3(n1)s3g_1 = \frac{\sum (x_i - \bar{x})^3}{(n - 1)s^3}

🗣 Hinglish Tip: Tail jidhar lambi ho → skewness udhar hoti hai


Types of Skewness

  1. Symmetric/Normal Distribution
  • Mean = Median = Mode
  • Skewness = 0
  • Bell shape curve

Normal Distribution


  1. Right-skewed/Positive Skewness
  • Mean > Median > Mode
  • Skewness > 0

Right-Skewed


  1. Left-skewed/Negative Skewness
  • Mean < Median < Mode
  • Skewness < 0

Left-Skewed


Kurtosis

Kurtosis measures the peakedness or flatness of the distribution.

It focuses on:

  • Height of the peak
  • Weight of the tails

Formula Population Kurtosis

β2=(xiμ)4Nσ4\beta_2 = \frac{\sum (x_i - \mu)^4}{N\sigma^4}

Excess Kurtosis

Excess Kurtosis=β23\text{Excess Kurtosis} = \beta_2 - 3

(3 is kurtosis of normal distribution)


Types of Kurtosis

Kurtosis TypeExcess KurtosisShape
Leptokurtic>0> 0Sharp peak, heavy tails
Mesokurtic=0= 0Normal distribution
Platykurtic<0< 0Flat peak, light tails

Kurtosis

🗣 Hinglish Tip: Kurtosis = curve kitni pointed ya flat hai


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