An Economist Is in the Process of Developing a Model $\left( x _ { 1 } \right)$

question 36

Essay

An economist is in the process of developing a model to predict the price of gold. She believes that the two most important variables are the price of a barrel of oil $\left( x _ { 1 } \right)$ and the interest rate $\left( x _ { 2 } \right)$ She proposes the first-order model with interaction: $y = \beta _ { 0 } + \beta _ { 1 } x _ { 1 } + \beta _ { 2 } x _ { 2 } + \beta _ { 3 } x _ { 1 } x _ { 3 } + \varepsilon$ .
A random sample of 20 daily observations was taken. The computer output is shown below.
THE REGRESSION EQUATION IS $y =$ $115.6 + 22.3 x _ { 1 } + 14.7 x _ { 2 } - 1.36 x _ { 1 } x _ { 2 }$ . $$\begin{array} { | c | r r c | } \hline \text { Predictor } & \text { Coef } & \text { SiDev } & T \\\hline \text { Constant } & 115.6 & 78.1 & 1.480 \\x _ { 1 } & 22.3 & 7.1 & 3.141 \\x _ { 2 } & 14.7 & 6.3 & 2.333 \\x _ { 1 } x _ { 2 } & - 1.36 & 0.52 & - 2.615 \\\hline\end{array}$$ S = 20.9 R-Sq = 55.4%. $$\begin{array}{l}\text { ANALYSIS OF VARIANCE }\\\begin{array} { | l | r r r c | } \hline \text { Source of Variation } & d f & \text { SS } & \text { MS } & F \\\hline \text { Regression } & 3 & 8661 & 2887.0 & 6.626 \\\text { Error } & 16 & 6971 & 435.7 & \\\hline \text { Total } & 19 & 15632 & & \\\hline\end{array}\end{array}$$ Is there sufficient evidence at the 1% significance level to conclude that the interest rate and the price of gold are linearly related?

---

Definitions:

Natural Concept

A type of concept that is understood through everyday experiences and interactions with the world, unlike formal concepts that are defined by specific sets of rules or characteristics.

Cognition

The mental action or process of acquiring knowledge and understanding through thought, experience, and the senses.

Triarchic Theory

A theory of intelligence proposed by Robert Sternberg, suggesting intelligence is composed of analytical, creative, and practical abilities.

Robert Sternberg

An American psychologist best known for his theory on intelligence and creativity, including the triarchic theory of intelligence.