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91Ó°ÊÓ

Government debt and population \(\quad\) Data used in this exercise was published by www.bloomberg.com for the most government debt per person for 58 countries and their respective population sizes in 2014 . When using population size (in millions) as the explanatory variable \(x,\) and government debt per person (in dollars) as the response variable \(y,\) the regression equation is predicted as government debt per person \(=19560.405-13.495\) population. a. Interpret the slope of the regression equation. Is the association positive or negative? Explain what this means. b. Predict government debt per person at the (i) minimum population size \(x\) value of 4 million, (ii) at the maximum population size \(x\) value of 1367.5 million. c. For India, government debt per person \(=\$ 946,\) and population \(=1259.7\) million. Find the predicted gov. ernment debt per person and the residual for India. Interpret the value of this residual.

Short Answer

Expert verified
The slope is -13.495, indicating a negative relationship. Predicted government debts are $19,506.43 for 4 million and $1,119.29 for 1367.5 million populations. India's residual of -$1,624.95 suggests its lower actual debt per person.

Step by step solution

01

Interpreting the Slope

The slope of the regression equation is -13.495. This indicates that for every increase of 1 million in population size, the government debt per person decreases by approximately $13.495. Since the slope is negative, the association between population size and government debt per person is negative.
02

Predicting Government Debt for 4 Million Population

Using the regression equation, plug in 4 for the population size:\[y = 19560.405 - 13.495 imes 4\]Calculate \(y\):\[y = 19560.405 - 53.98 = 19506.425\]Thus, the predicted government debt per person for a population of 4 million is $19,506.43.
03

Predicting Government Debt for 1367.5 Million Population

Using the regression equation, plug in 1367.5 for the population size:\[y = 19560.405 - 13.495 imes 1367.5\]Calculate \(y\):\[y = 19560.405 - 18441.1125 = 1119.2925\]Thus, the predicted government debt per person for a population of 1367.5 million is $1,119.29.
04

Finding Predicted Debt for India

Using the regression equation, plug in 1259.7 for the population size:\[y = 19560.405 - 13.495 imes 1259.7\]Calculate \(y\):\[y = 19560.405 - 16989.4515 = 2570.9535\]Thus, the predicted government debt per person for India's population is approximately $2,570.95.
05

Calculating the Residual for India

The residual is the difference between the observed and predicted government debt per person. For India, the observed debt is \(946.\[\text{Residual} = 946 - 2570.9535 = -1624.9535\]The negative residual means India's actual government debt per person is \)1,624.95 less than predicted.
06

Interpreting the Residual

The negative residual indicates that India's government debt per person is significantly lower than what the regression model predicts. This could suggest that, relative to its population, India has managed its debt per person better than other countries in the analyzed data set.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Slope Interpretation
In regression analysis, the slope of the equation reveals the relationship between the explanatory and response variables. Let's break it down using the regression equation provided: - The slope in the equation, -13.495, tells us how much the government debt per person changes when the population size increases by one unit (or in this case, by 1 million people). - With a negative slope, as we see here, there's an inverse relationship. It means that for every increase of 1 million people in population size, the government debt per person decreases by approximately $13.495. This negative association conveys an essential insight that larger populations tend to have lesser government debt per person, according to this model. Understanding the slope helps us predict how changes in population size might inversely affect government debt per person in different scenarios.
Predictive Modeling
Predictive modeling, in this context, refers to using the regression equation to make predictions about government debt per person for different population sizes. Here's how it operates:- By substituting a specific population value (\(x\)) into the equation, we can compute an expected value for government debt per person (\(y\)).- For example, with a population size of 4 million, we plug the number into the equation: \[y = 19560.405 - 13.495 \times 4 \] which results in a predicted debt of \(19,506.43 per person.- Similarly, for a massive population size like 1367.5 million, the equation \[y = 19560.405 - 13.495 \times 1367.5 \] gives us a prediction of \)1,119.29 per person.Predictive modeling is powerful as it allows us to foresee potential outcomes and make informed decisions based on predicted data patterns.
Residual Calculation
Residual calculation is crucial for understanding the accuracy of predictions made by a regression model. Here's its role in this analysis:- The residual is the difference between the observed value and the predicted value of government debt per person. - For India, where the actual government debt per person is \(946, the predicted debt from the model is approximately \)2,570.95.- Calculating the residual, \[ ext{Residual} = 946 - 2570.95 = -1624.95 \]reveals that the model's prediction was higher by $1,624.95 than the actual amount.A negative residual, as seen here, suggests that the actual debt is less than the predicted debt, indicating a better economic situation than expected by the model's trends. Residuals help identify discrepancies and improve model reliability where needed.

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Most popular questions from this chapter

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