Math Problem Statement

Consider the following variables for X and y X / y 2 / 4 3 / 5 4 / 4 5 / 6 7 / 4 7 / 6 7 / 9 8 / 5 9 / 11 Perform a logarithmic transformation on the dependent variable y. Develop an estimated regression equation using the transformed dependent variable

Solution

To perform a logarithmic transformation on the dependent variable yy, we need to take the natural logarithm (ln) of each yy value, then develop a linear regression equation using XX as the independent variable and ln(y)\ln(y) as the dependent variable.

Step 1: Logarithmic Transformation of yy

We compute ln(y)\ln(y) for each value of yy:

X & y & \ln(y) \\ \hline 2 & 4 & \ln(4) \approx 1.386 \\ 3 & 5 & \ln(5) \approx 1.609 \\ 4 & 4 & \ln(4) \approx 1.386 \\ 5 & 6 & \ln(6) \approx 1.792 \\ 7 & 4 & \ln(4) \approx 1.386 \\ 7 & 6 & \ln(6) \approx 1.792 \\ 7 & 9 & \ln(9) \approx 2.197 \\ 8 & 5 & \ln(5) \approx 1.609 \\ 9 & 11 & \ln(11) \approx 2.398 \\ \end{array}$$ ### Step 2: Perform Linear Regression Now, we need to estimate a linear regression model of the form: $$\ln(y) = a + bX$$ Using the data points $$X$$ and $$\ln(y)$$, we can compute the coefficients $$a$$ (intercept) and $$b$$ (slope) using the least-squares method. Let me calculate the regression coefficients for you.The estimated regression equation after performing the logarithmic transformation on $$y$$ is: $$\ln(y) = 1.182 + 0.095X$$ This equation represents the relationship between $$X$$ and the natural logarithm of $$y$$, where the intercept is approximately 1.182 and the slope is 0.095. Would you like more details on this process or have any questions? Here are 5 related questions to deepen understanding: 1. How does a logarithmic transformation help in regression analysis? 2. What are the assumptions of linear regression? 3. How can we interpret the slope and intercept in this transformed model? 4. Can you revert the logarithmic transformation to predict actual $$y$$ values? 5. What are the advantages of transforming the dependent variable in non-linear data? **Tip:** When interpreting coefficients in a log-transformed model, a one-unit increase in $$X$$ corresponds to approximately a percentage change in $$y$$, not a simple linear increase.

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Math Problem Analysis

Mathematical Concepts

Logarithmic Transformation
Linear Regression
Natural Logarithm

Formulas

ln(y) = a + bX
Natural logarithm: ln(y)
Least squares method

Theorems

Linear Regression Theorem

Suitable Grade Level

College level