Notation

Description Example Meaning
Letter y \(Y\) Represent the dependent (random) variable (number or binary indicator)
Lower case i \(y_i\) Identifies one specific observation
Lower case n \(n\) Number of observations in the data available for modelling
Lower case p \(p\) Number of explanatory variables
Caligraphic X \(\mathcal{X} = \mathcal{R}^p\)

\(\underline{x}_i \ni \mathcal{X}\)
P-dimensional space
An asterisk in the subscript \(x_*\) An observation of interest