Math Problem Statement

Suppose we want to use data on square footage to predict home sale prices. An equation that fits the data below reasonably well is

Predicted Selling Price=32.98+0.14(Square Footage).

In order to find the sum of squared errors for this data, we have constructed the following table.

Housing Prices and Square Footage Observed Selling Price (Thousands of Dollars) Observed Square Footage Predicted Selling Price (Thousands of Dollars) Error Squared Error 227.6 1428 232.90 − 5.30 28.0900 257.2 1494 242.14 15.06 226.8036 269.4 1694 270.14 − 0.74 0.5476 203.5 1214 202.94 0.56 0.3136 225.4 1399 228.84 − 3.44 11.8336 217.4 1291 213.72 3.68 13.5424 182.2 1193 200.00 −17.80 316.8400 184.8 1006

Find the missing values in the table for an observed selling price of 184.8 and square footage of 1006 . Round your answers to two decimal places, if necessary.

Solution

We are given the following equation for the predicted selling price based on square footage:

Predicted Selling Price=32.98+0.14×(Square Footage)\text{Predicted Selling Price} = 32.98 + 0.14 \times (\text{Square Footage})

We need to find the missing values in the table for an observed selling price of 184.8 and a square footage of 1006. Let's work through the steps:

  1. Predicted Selling Price: Using the equation to find the predicted selling price for 1006 square feet:

Predicted Selling Price=32.98+0.14×1006=32.98+140.84=173.82 (thousands of dollars)\text{Predicted Selling Price} = 32.98 + 0.14 \times 1006 = 32.98 + 140.84 = 173.82 \text{ (thousands of dollars)}

  1. Error: The error is calculated as the difference between the observed selling price and the predicted selling price:

Error=Observed Selling PricePredicted Selling Price=184.8173.82=10.98 (thousands of dollars)\text{Error} = \text{Observed Selling Price} - \text{Predicted Selling Price} = 184.8 - 173.82 = 10.98 \text{ (thousands of dollars)}

  1. Squared Error: The squared error is calculated by squaring the error:

Squared Error=(Error)2=(10.98)2=120.56\text{Squared Error} = (\text{Error})^2 = (10.98)^2 = 120.56

Updated table for the last row:

Observed Selling Price (Thousands of Dollars)Observed Square FootagePredicted Selling Price (Thousands of Dollars)ErrorSquared Error
184.81006173.8210.98120.56

Summary of findings:

  • Predicted Selling Price = 173.82 (thousands of dollars)
  • Error = 10.98 (thousands of dollars)
  • Squared Error = 120.56

Let me know if you need further clarification or have any other questions! Here are some related questions:

  1. How do you calculate the total sum of squared errors for the entire dataset?
  2. What does the squared error represent in the context of predicting housing prices?
  3. How would the prediction equation change if we added more variables (e.g., number of bedrooms)?
  4. What does a large squared error imply about the accuracy of the model's predictions?
  5. How would you interpret a negative error in terms of model accuracy?

Tip: If you’re working with a model, always check for consistency in predictions, and try different types of error analysis (like root mean squared error) to assess accuracy more thoroughly.

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Math Problem Analysis

Mathematical Concepts

Linear Regression
Error Calculation
Squared Error

Formulas

Predicted Selling Price = 32.98 + 0.14 × Square Footage
Error = Observed Selling Price - Predicted Selling Price
Squared Error = (Error)^2

Theorems

Least Squares Method

Suitable Grade Level

Grades 9-12