Single equation regression models: -The dependent variable, Y, is expressed as a linear function of one or more explanatory variables, the Xs. Assumption the cause-and-effect relationship, if any, between Y and the Xs is unidirectional: explanatory variables are the cause; the dependent variable is the effect
11.1 The Nature of Heteroscedasticity Homoscedasticity: equal variance. Heteroscedasticity: unequal variance. Heteroscedasticity is usually found in cross-sectional data
Multiple Regression Model: A regression model with more than one explanatory variable, multiple because multiple nfluences (i.e., variables)affect the dependent variable
5.1 The Meaning of Regression Analysis 1.Regression analysisthe study of the relationship between one variable Y (the explained, or dependent variable) and one or more other variables X/Xs (explanatory, or independent variables)
The Normal Distribution: the distribution of a continuous r.v. whose value depends on a number of factors, yet no single factor dominates the other. 1. Properties of the normal distribution: 1)The normal distribution curve is symmetrical around its mean valueu. 2)The PDF of the distribution is the highest at its mean value but tails off at its extremities
Definition (1) Econometrics: economic measurement. (2) Econometrics: the social science in which the tools of economic theory, mathematics, and statistical inference are applied to the analysis of economic phenomena. (3) Econometrics: the result of a certain outlook on the role of economics, consists of the application of mathematical statistics to economic data to lend
