SPURIOUS CORRELATION AND IT'S DETECTION

RANDOMIZATION

The reason statisticians design experiments and then randomly execute them is to try and eliminate the effect of concomitant or "lurking variables". If all the experiments at the "low level" of a variable are performed before the experiments at the "high level", there is a chance that a background or unknown variable may be the real cause of the significant difference between two means. The social scientist unable to design and randomize and replicate must be ever careful of the "lurking variables". Lurking variables, like the time frame example in the Demand For Gas study are identified when the augmented model using Intervention Series causes the conditional impact of the heretofore significant X variable to be non-significant. Another example of exposing a Lurking Variable is the Australian Wine Study. As soon as the model was augmented with the ARIMA structure, a proxy for population, the statistical significance of the Italian car registration vanishes.

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