The notation for panel data is $\left( X _ { i t } , Y _ { i t } \right) , i = 1 , \ldots , n \text { and } t = 1 , \ldots , T$
because
A) we take into account that the entities included in the panel change over time and are replaced by others.
B) the X 's represent the observed effects and the Y the omitted fixed effects.
C) there are n entities and T time periods.
D) n has to be larger than T for the OLS estimator to exist.

Question

The notation for panel data is $\left( X _ { i t } , Y _ { i t } \right) , i = 1 , \ldots , n \text { and } t = 1 , \ldots , T$
because
A) we take into account that the entities included in the panel change over time and are replaced by others.
B) the  X  's represent the observed effects and the  Y  the omitted fixed effects.
C) there are  n  entities and  T  time periods.
D)  n  has to be larger than  T  for the OLS estimator to exist.

Quizplus · Accepted Answer

Panel data notation $(X_{it}, Y_{it})$ indicates that there are $n$ entities and $T$ time periods, with each entity observed across all time periods.

The Notation for Panel Data Is (Xit,Yit),i=1,…,n and t=1,…,T\left( X _ { i t } , Y _ { i t } \right) , i = 1 , \ldots , n \text { and } t = 1 , \ldots , T(Xit​,Yit​),i=1,…,n and t=1,…,T

The Notation for Panel Data Is $\left( X _ { i t } , Y _ { i t } \right) , i = 1 , \ldots , n \text { and } t = 1 , \ldots , T$