Principal Component MTWe often meet difficulties in the calculation of MD. If we meet, we find important hints to solve problems when we consider the Sampling of data.
In Cause and Effect Analysis , the difficulties are the chance to get bif hints to solve problems.
We should ignore the variable because the variable is not effect the phenomena.
Why the difference of variance?" may be the hint to solve the phenomena.
Only a variable of multicollinearity variables is needed. The others are not needed because multicollinearity means we can not understand the difference of variables.
The time multicollinearity appears" may be the hint to solve the phenomena.
