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

1.3.3.15.1.

Lag Plot: Random Data

Lag Plot

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 Y_i-1, the next value Y_i. Thus for a known value Y_i-1 on the horizontal axis (say, Y_i-1 = +0.5), the Y_i-th value could be virtually anything (from Y_i = -2.5 to Y_i = +1.5). Such non-association is the essence of randomness.