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In Example \(2,\) the prediction equation between \(y=\) selling price and \(x_{1}=\) house size and \(x_{2}=\) number of bedrooms $$\text { was } \hat{y}=60,102+63.0 x_{1}+15,170 x_{2}$$ a. For fixed number of bedrooms, how much is the house selling price predicted to increase for each square foot increase in house size? Why? b. For a fixed house size of 2000 square feet, how does the predicted selling price change for two, three, and four bedrooms?

Short Answer

Expert verified
a. Predicted price increases by $63 per square foot increase. b. Predicted price is $216,442 for 2 bedrooms, $231,612 for 3 bedrooms, $246,782 for 4 bedrooms.

Step by step solution

01

Identify the relationship between variables

We have the prediction equation: \( \hat{y} = 60,102 + 63.0x_1 + 15,170x_2 \). The coefficients of \( x_1 \) and \( x_2 \) represent how changes in these variables affect the predicted selling price \( \hat{y} \).
02

Determine the impact of house size on price

Keeping \( x_2 \) (number of bedrooms) constant means we focus on the coefficient of \( x_1 \), which is 63. Therefore, for each additional square foot increase in house size, the selling price is predicted to increase by \( 63.0 \) dollars.
03

Calculate price changes with fixed house size

When \( x_1 \), the house size, is fixed at 2000 square feet, we examine the effect of changes in the number of bedrooms \( x_2 \). Calculate the predicted prices for different values of \( x_2 \):- For 2 bedrooms: \( \hat{y} = 60,102 + 63.0 \times 2000 + 15,170 \times 2 \).- For 3 bedrooms: \( \hat{y} = 60,102 + 63.0 \times 2000 + 15,170 \times 3 \).- For 4 bedrooms: \( \hat{y} = 60,102 + 63.0 \times 2000 + 15,170 \times 4 \).
04

Perform calculations for fixed house size scenarios

Calculate each scenario:- For 2 bedrooms: \( \hat{y} = 60,102 + 126,000 + 30,340 = 216,442 \).- For 3 bedrooms: \( \hat{y} = 60,102 + 126,000 + 45,510 = 231,612 \).- For 4 bedrooms: \( \hat{y} = 60,102 + 126,000 + 60,680 = 246,782 \).
05

Analyze the results

With a fixed house size, the selling price increases by \( 15,170 \) for each additional bedroom. This is evident from the differences in predicted prices as the number of bedrooms changes.

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Key Concepts

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

Prediction Equation
The prediction equation in multiple linear regression is an essential tool used to estimate the outcome variable based on one or more predictor variables. In this context, the equation for predicting the selling price of a house is given as:\[ \hat{y} = 60,102 + 63.0 x_1 + 15,170 x_2 \] where:
  • \( \hat{y} \) is the predicted selling price.
  • \( x_1 \) represents the house size (in square feet).
  • \( x_2 \) stands for the number of bedrooms.
This equation reflects a linear relationship, meaning the predicted selling price changes linearly with variations in either the house size or the number of bedrooms. The numerical values such as 60,102, 63.0, and 15,170 are vital to understand as they indicate the base price and the impact of each unit change in the independent variables respectively. This serves as a blueprint for analyzing how different factors contribute to the overall selling price.
Coefficients
Coefficients in a prediction equation are crucial as they dictate how much the dependent variable is expected to change with a one-unit change in an independent variable, assuming all other variables remain constant. In our equation:
  • The coefficient for \( x_1 \) (house size), 63.0, tells us that for each additional square foot of house size, the selling price is predicted to increase by \(63.
  • The coefficient for \( x_2 \) (number of bedrooms), 15,170, indicates that for each additional bedroom, the selling price is expected to rise by \)15,170, given a constant house size.
These coefficients are determined through statistical analysis and provide insights into which factors significantly affect the selling price. By understanding the magnitude and direction of these coefficients, one can make informed decisions about property features that influence market value.
Selling Price Analysis
Analyzing selling price using a prediction equation allows us to estimate the impact of different housing features. Let's see how the selling price is affected under various conditions:When the number of bedrooms is fixed and we increase the house size, the increase in price follows directly from the coefficient of \( x_1 \) which is 63.0. Hence, with each square foot increase, the selling price grows by $63.Now, let's maintain the house size at 2000 square feet and vary the number of bedrooms:
  • For two bedrooms, the predicted price is 216,442 dollars.
  • For three bedrooms, the predicted price rises to 231,612 dollars.
  • Adding a fourth bedroom further escalates the predicted price to 246,782 dollars.
This analysis shows that the number of bedrooms has a substantial impact on the predicted selling price, highlighting the importance of modeling different scenarios to understand market dynamics.
Independent Variables
In multiple linear regression, independent variables such as house size \( x_1 \) and number of bedrooms \( x_2 \) play a pivotal role. These variables are used to predict changes in the dependent variable, which is the selling price \( \hat{y} \) in our example. An independent variable is a factor that is hypothesized to influence the dependent variable.Understanding their influence involves:
  • Recognizing that each independent variable carries a weight (coefficient) that suggests its impact on the dependent variable.
  • Knowing that independent variables can be manipulated for decision-making purposes in real-estate; homeowners might enhance their home in ways to increase selling prices.
By accurately incorporating these independent variables into a prediction equation, stakeholders can better predict outcomes and make informed decisions in housing markets. This involves not only selling prices but also potential modifications to enhance property value.

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Most popular questions from this chapter

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