Math Problem Statement

Multiple regression was performed on the cars dataset with quality as the response variable and speed and angle as the predictor variables. The following fitted values and residuals were obtained.

import pandas as pd import statsmodels.formula.api as sms

cars = pd.read_csv('http://data-analytics.zybooks.com/Cars.csv')

Response variable

Y = cars['Quality']

Generates the linear regression model

Multiple predictor variables are joined with +

model = sms.ols('Y ~ Speed + Angle', cars).fit()

print(model.fittedvalues) 0 0.756997 1 2.661578 2 2.880407 3 5.003817 4 4.784987 5 7.127226 6 6.689567 7 6.908397 8 9.250636 9 10.717557 10 13.059796 11 11.374046 12 12.840967 13 13.278626 14 14.964377 15 17.087786 16 19.211196 17 15.402036 dtype: float64 print(model.resid) 0 1.243003 1 0.338422 2 -0.880407 3 -1.003817 4 0.215013 5 0.872774 6 -0.689567 7 1.091603 8 -1.250636 9 -0.717557 10 0.940204 11 -0.374046 12 -0.840967 13 -0.278626 14 0.035623 15 0.912214 16 -0.211196 17 0.597964 dtype: float64

Based on the output, what is the second regression fitted value? Type as: #.######

Solution

To determine the second regression fitted value, we refer to the output of model.fittedvalues. The second fitted value corresponds to the index 1 (Python indexing starts at 0). From the output provided:

Second regression fitted value = 2.661578

Let me know if you'd like to discuss further or explore the residuals, interpretations, or any related concepts! Here are some related questions:

  1. How are fitted values calculated in a multiple regression model?
  2. What does a residual represent in this context?
  3. How can we use residuals to evaluate the goodness of fit?
  4. What is the significance of predictor variables in multiple regression analysis?
  5. How do we interpret the coefficients of Speed and Angle from the model?

Tip: When analyzing regression output, always check the residuals to identify patterns or potential issues with the model.

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Math Problem Analysis

Mathematical Concepts

Statistics
Linear Regression
Multiple Regression

Formulas

Y = β0 + β1 * Speed + β2 * Angle

Theorems

Ordinary Least Squares (OLS)

Suitable Grade Level

Undergraduate