(Requires Appendix material)A necessary and sufficient condition to derive the OLS estimator is that the following two conditions hold: 
= 0 and 
= 0.Show that these conditions imply that 
= 0.
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The group of people who are employed by a particular company, industry, or economy at large.
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A country in North America, consisting of 50 states, a federal district, and five major self-governing territories.
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