Judge of Abnormal Value

Judge of Outlier is also used to judge of abnormal value.

But outlier is the part of abnormal values.

Abnormal Value
For example, in the data of the figure, there is a strange balue. But this data is not outlier.

But in this case, after some work, we can use the judge of outlier.

By Difference of Prediction and Actual

In the case of above, prediction is the value if it is a SIN curve.

If it is the SIN curve, the difference of the abnormal point is large. And we can use the data as outlier.

Prediction is defined by the definition of normal.

In the case of above, diffence between 1 step is small. We can define the difference to judge of outlier.

If there is the experience of abnormal, normal is defined by comparing the abnormal.

FMEA and FTA are the approaches to study the mechanism totally.