Raw Moments

The nth raw moment about zero is the expected value of Xn.

1st raw moment:

2nd raw moment = mean

3rd raw moment:

4th raw moment:

For the data (1, 2, 2, 4, 6), the raw moments can be found as follows:

x x2 x3 x4
1111
24816
24816
41664256
6362161296
sum15612971585
μ'i312.259.4317
μ'i: ith raw moment

Central Moments

Central moments are moments about the mean.

1st central moment (m1)

2nd central moment (m2) = variance

3rd central moment (m3)

4th central moment (m4)

where

For the data (1, 2, 2, 4, 6), the mean is 3. Therefore,

x d d2 d3 d4
1-24-816
2-11-11
2-11-11
41111
6392781
sum1501618100
mi03.23.620
mi: ith central moment d = x - mean

Standardized Moments

The standardized moment is a moment that has normalized.

1st standardized moment (a1)

2nd standardized moment (a2)

3rd standardized moment (a3)

4th standardized moment (a4)

where

For the data (1, 2, 2, 4, 6), the mean is 3 and the standard deviation is 1.79. Therefore,

x z z2 z3 z4
1-1.1181.250-1.3981.563
2-0.5590.313-0.1750.098
2-0.5590.313-0.1750.098
40.5590.3130.1750.098
61.6772.8134.7177.910
sum150.0005.0003.1449.766
ai0.0001.000 0.629 1.953
ai: ith standardized moment z = (x - mean) / standard deviation