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Module 2: Data Mining and Association Rule Mining

20205m

Use the two methods below to normalize the following group of data:

200; 300; 400; 600; 1000

  • min-max normalization by setting min = 0 and max = 1
  • z-score normalization
Worked SolutionAI Assisted

Normalizing Data: 200, 300, 400, 600, 1000

Method 1: Min-Max Normalization (new_min=0, new_max=1)

v=vminmaxmin×(new_maxnew_min)+new_minv' = \frac{v - min}{max - min} \times (\text{new\_max} - \text{new\_min}) + \text{new\_min}

Here min=200min = 200, max=1000max = 1000, range =800= 800, new_min=0, new_max=1, so simply:
v=v200800v' = \frac{v - 200}{800}

v Calculation v'
200 (200-200)/800 0.000
300 (300-200)/800 0.125
400 (400-200)/800 0.250
600 (600-200)/800 0.500
1000 (1000-200)/800 1.000

Method 2: Z-Score Normalization

v=vμσv' = \frac{v - \mu}{\sigma}

Mean: μ=200+300+400+600+10005=25005=500\mu = \dfrac{200+300+400+600+1000}{5} = \dfrac{2500}{5} = 500

Variance (population):
σ2=(200500)2+(300500)2+(400500)2+(600500)2+(1000500)25\sigma^2 = \frac{(200-500)^2+(300-500)^2+(400-500)^2+(600-500)^2+(1000-500)^2}{5}
=90000+40000+10000+10000+2500005=4000005=80000= \frac{90000+40000+10000+10000+250000}{5} = \frac{400000}{5} = 80000

Std dev: σ=80000282.84\sigma = \sqrt{80000} \approx 282.84

v v − μ z = (v−μ)/σ
200 −300 −1.06
300 −200 −0.71
400 −100 −0.35
600 +100 +0.35
1000 +500 +1.77

Summary

Original Min-Max [0,1] Z-Score
200 0.000 −1.06
300 0.125 −0.71
400 0.250 −0.35
600 0.500 +0.35
1000 1.000 +1.77

Min-max squeezes everything cleanly into [0,1] (bounded by the observed extremes), while z-score centers the data at 0 with unit spread — the value 1000, being furthest from the mean, gets the largest magnitude z-score (+1.77), reflecting how much of an outlier it is relative to the rest of the group.

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