Your Textbook Derives the OLS Estimator As $\hat { \beta }$

question 31

Essay

Your textbook derives the OLS estimator as $\hat { \beta }$ = $\left( X ^ { \prime } \right.$ X)^-1
$X ^ { \prime }$ ^Y.
Show that the estimator does not exist if there are fewer observations than the number of explanatory variables, including the constant. What is the rank of $X ^ { \prime }$ X in this case?

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Definitions:

Symptoms Develop

The emergence or manifestation of signs or indicators of a disease or medical condition in an individual.

Nursing Diagnosis

A professional evaluation of an individual's, family's, or community's response to existing or possible health issues or life events.

Professional Image

The perception or impression one projects in a professional setting, often influenced by behavior, attire, and communication.

Physician's Role

The responsibilities and duties of a physician, including diagnosing and treating illnesses, prescribing medication, and providing guidance on health maintenance and disease prevention.