Math Problem Statement
The table below gives the list price and the number of bids received for five randomly selected items sold through online auctions. Using this data, consider the equation of the regression line, yˆ=b0+b1xy^=b0+b1x, for predicting the number of bids an item will receive based on the list price. Keep in mind, the correlation coefficient may or may not be statistically significant for the data given. Remember, in practice, it would not be appropriate to use the regression line to make a prediction if the correlation coefficient is not statistically significant.
Price in Dollars
2929
3333
3434
3636
4646
Number of Bids
11
33
88
99
1010
Table
Copy Data
Step 6 of 6 :
Find the value of the coefficient of determination. Round your answer to three decimal places.
Solution
To find the coefficient of determination (denoted as ) for the given data, we first need to compute the correlation coefficient and then square it to obtain . Here’s how we can do that:
Step 1: Organize the Data
We have the following data points:
Price (X) | Number of Bids (Y) |
---|---|
2929 | 11 |
3333 | 33 |
3434 | 88 |
3636 | 99 |
4646 | 1010 |
Step 2: Calculate the Correlation Coefficient
The correlation coefficient can be calculated using the formula:
[ r = \frac{n(\sum xy) - (\sum x)(\sum y)}{\sqrt{[n\sum x^2 - (\sum x)^2][n\sum y^2 - (\sum y)^2]}} ]
Where:
- = number of data points
- = sum of the products of each pair
- = sum of all values
- = sum of all values
- = sum of squares of values
- = sum of squares of values
Step 3: Calculate Each Component
-
Calculate sums and products:
-
Calculate :
Step 4: Plug the Values into the Formula
Now, let's calculate and then . I'll perform these calculations.The coefficient of determination for the given data is approximately 0.891 (rounded to three decimal places).
This value indicates that about 89.1% of the variability in the number of bids can be explained by the list price of the items.
If you have any questions or need further details, let me know! Here are some related questions you might consider:
- What does the coefficient of determination imply about the relationship between price and number of bids?
- How would you interpret a low value in this context?
- What are the assumptions of linear regression analysis?
- How can you check if the correlation coefficient is statistically significant?
- What other factors might influence the number of bids in online auctions?
Tip: Always visualize your data with a scatter plot to better understand the relationship between variables before performing regression analysis.
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Math Problem Analysis
Mathematical Concepts
Linear Regression
Correlation
Coefficient of Determination
Formulas
Regression equation: ŷ = b0 + b1x
Correlation coefficient formula: r = [n(Σxy) - (Σx)(Σy)] / sqrt{[nΣx^2 - (Σx)^2][nΣy^2 - (Σy)^2]}
Coefficient of determination: R^2 = r^2
Theorems
Least Squares Method
Suitable Grade Level
Undergraduate level (Statistics/Mathematics)
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