Regression advanced
8 important questions on Regression advanced
What should one do when there are categorical and quantitative PV's in the analysis?
What happens with the graph when a dummy variable is added?
B*0 = 0
B*1 = B
In this case B is a fixed number and can be added to the Alpha
What should be done if the categorical PV that has to be changed to dummy variable has more than two categories?
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Is multicollinearity a problem?
No because it is not a problem for the reliability of the whole model
Yes because it is unclear to what extent a PV has a contribution to the OV.
How van multicollinearity be measured?
Tolerance: <0,10 = serious collinearity, 0,10-0,20 = collinearity, not to severe, >0,20 = no collinearity
VIF: <5 is no collinearity, 5-10 = collinearity, not to severe, >10 = serious collinearity
By computing Tolerance, one should use Rj^2. This is not the general R^2, but the one that is allocated to the specific PV.
What is a moderator?
What is a mediator?
For instance: Relation between stress and bodyweight is negative (more stress is less weight)
But, stress causes perhaps sugar consumption, which rises body weight. sugar consumption is a mediator.
Why does one use non-parametric tests?
A non-parametric test is assumption free and has fewer assumptions about the distribution because it measures different measures, not the actual data
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