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1. Exploratory Data Analysis
1.3. EDA Techniques
1.3.3. Graphical Techniques: Alphabetic Lag Plot

Lag Plot: Random Data

Lag Plot lag plot showing randomness, no autocorrelation, and no outliers
Conclusions We can make the following conclusions based on the above plot of 200 normal random numbers.
  1. The data are random.
  2. The data exhibit no autocorrelation.
  3. The data contain no outliers.
Discussion The lag plot shown above is for lag = 1. Note the absence of structure. One cannot infer, from a current value Yi-1, the next value Yi. Thus for a known value Yi-1 on the horizontal axis (say, Yi-1 = +0.5), the Yi-th value could be virtually anything (from Yi = -2.5 to Yi = +1.5). Such non-association is the essence of randomness.
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