Sunday, January 10, 2021

The role of linear regression continued..

 Non-linear equations can also be "linearized" by selecting a suitable change of variables.  This is quite popular because it makes the analysis simpler. But reducing the dimensions is prone to distortion of the error structure. It is an oversimplification of the model.  It violates key assumptions and impacts the resulting parameter values. All of this contributes toward incorrect predictions and are best avoided.  Non-linear squares analysis has well-defined techniques that are not too difficult with computing. Therefore, it is better to do non-linear square analysis when dealing with non-linear inverse models. 

Linear regression differs from correlation. The correlation coefficient describes the strength of the association between two variables. If the two variables, the correlation coefficient tends to +1. If one decreases as the other increases, the correlation coefficient tends to -1.  If they are not related to one another, the correlation coefficient stays at zero. In addition, the correlation coefficient can be related to the results of the regression. This is helpful because we now find a correlation not between parameters but between our notions of cause and effect. This also leads us to use the correlation between any x and y which are not necessarily independent and dependent variables.  This follows from the fact that the correlation coefficient (denoted by r) is symmetric in x and y. This differentiates the coefficient from the regression.

Service Requests have many attributes in addition to category. These attributes include joins with other tables that describe the affected product, its version, the number of customers impacted and the likes of this place. When the service requests are filtered by one or more of these attributes, they tend to form requests that display scatter plots suitable for linear regression. It is very helpful to use these linear regressions to predict the next data point especially given that the data points are progressing along the timeline. 


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