For example, the number of people having hot coffee and the number of people taking sauna bath in gym may not be caused by each other. However, coldness may be reasons for both events. However, it is not necessary that one or the other may cause two variables, which are changing simultaneously, can be cause of any one. For example, the speed of wind and the number of cars on the road are not associated to each other. It is important to note that the symptoms must not be considered as cause. For example, B is caused by A and C is caused by B. Actually that not the case. C is also caused by A. B is just the symptom of A, which cannot be considered as cause.
The statistician should be aware of averages when computing for extreme values i.e. have outliers. Averages cannot be applied in this case, however if you remove the extreme values, which are in outliers, only then you can you averages. ...Show more