Microsoft founder and tech prodigy Bill Gates.

Sigma Chi (ΣΧ) is one of the largest Greek-letter secret and social fraternities in North America with 244 active chapters in the United States and Canada and more than 300,000 initiates. Sigma Chi was founded on June 28, 1855 at Miami University in Oxford, Ohio when members split from Delta Kappa Epsilon. Sigma Chi has seven founding members: Benjamin Piatt Runkle, Thomas Cowan Bell, William Lewis Lockwood, Isaac M. Jordan, Daniel William Cooper, Franklin Howard Scobey, and James Parks Caldwell. Sigma Chi is a part of the Miami Triad, along with Beta Theta Pi and Phi Delta Theta.

Instrumental variable methods allow consistent estimation when the explanatory variables (covariates) are correlated with the error terms of a regression relationship. Such correlation may occur when the dependent variable causes at least one of the covariates (“reverse” causation), when there are relevant explanatory variables which are omitted from the model, or when the covariates are subject to measurement error. In this situation, ordinary linear regression generally produces biased and inconsistent estimates. However, if an instrument is available, consistent estimates may still be obtained. An instrument is a variable that does not itself belong in the explanatory equation and is correlated with the endogenous explanatory variables, conditional on the other covariates. In linear models, there are two main requirements for using an IV:

The instrument must be correlated with the endogenous explanatory variables, conditional on the other covariates.
The instrument cannot be correlated with the error term in the explanatory equation, that is, the instrument cannot suffer from the same problem as the original predicting variable.

Exogenous refers to an action or object coming from outside a system. It is the opposite of endogenous, something generated from within the system.

In an economic model, an exogenous change is one that comes from outside the model and is unexplained by the model. For example, in the simple supply and demand model, a change in consumer tastes or preferences is unexplained by the model and also leads to endogenous changes in demand that lead to changes in the equilibrium price. Similarly, a change in the consumer’s income is given outside the model. Put another way, an exogenous change involves an alteration of a variable that is autonomous, i.e., unaffected by the workings of the model.

Robert Raimon Roy is the artists full name. This is a recent conversion from his former stage name “Rob Roy” under which he produced the song “Fur in my Cap.” While the song did reach critical acclaim, Roy has mentioned that his new (full) name represents a change from who he was and to demonstrate the progress he has made as a person and artist.

—>