# Data Mining - Global vs Local

Global refers to calculation that are made over the whole data set whereas local refers to calculations that are made local to a point or a partition.

## 3 - High dimension vs Local

In high dimension, it's really difficult to stay local.

Example: the percentage of volume that contains 10% of the data in an hypercube is:

• Two dimension: $1^2 - 0.9^2 = 1 - 0.81 = 0.19 = 19\%$
• Ten dimensions: $1^{10} - 0.9^{10} = 1 - 0.35 = 0.65 = 65\%$

To resolved this problem, (structured|parametrized) model have been introduced. The simplest one is the linear model.