Chapter 3 Flashcards
is the study of the relationships between a dependent variable (Y) and one or more independent or explanatory variables (X1, X2,..).
Regression
is Population Regression Function (PRF) or Population Regression (PR).
- E(Y|X=Xi) = f(Xi)
- It states merely that the expected value of the distribution of Y given Xi is functionally related to Xi.
Population Regression Function (PRF) or Population Regression (PR).
In simple terms, it tells how the mean or average response of Y varies with X
Population Regression Function (PRF) or Population Regression (PR).
Linearity in variable
The conditional mean of the dependent variable is a linear function of the independent variables. A function Y = f(X) is linear if
X appears with a power of 1 only (no X2 or √X)
X is not multiplied or divided by another variable
Linearity in parameters
- The conditional mean of the dependent variable is a linear function of the parameters. if A function is linear in the parameter β1,
if β2 appears with a power of 1 only.
Stochastic disturbance or stochastic error term.
Ui
It is nonsystematic component
- Ui = Stochastic disturbance or stochastic error term
is systematic or deterministic. It is the mean consumption expenditure of all the families with the same level of income
- Component E(Y|X=Xi )
- The assumption that the regression line passes through the conditional means of Y implies that
E(Ui|Xi) = 0
This is a surrogate for all variables that are omitted from the model but they collectively affect Y
Ui
Why not include as many as variable into the model (or the reasons for using ui )
Vagueness of theory
Unavailability of Data
Core Variables vs. Peripheral Variables
Intrinsic randomness in human behavior
Poor proxy variables
Principle of parsimony
Wrong functional form
A particular numerical value obtained by the estimator in an application
Estimate
SRF in stochastic form
Yi= B^1 +B^2X1+ U^i or Y^i + U^1
Primary objective in regression analysis
Estimate the PRF on the Basis of SRF. And how to construct B^1 close to B1 and B^2 close to B2 as much as possible