Math Problem Statement

Regression analysis was applied between sales data (y in $1,000s) and advertising data (x in $100s) and the following information was obtained. ŷ = 12 + 1.8x n = 16 SSR = 126 SSE = 42 sb1 = 0.2777 The F statistic computed from the above data is 42. What is the p-value for the F test?

Solution

To determine the p-value for the F-test, we follow these steps:

  1. Understand the F-test setup: The F-statistic in this context is used to test the null hypothesis: H0:β1=0H_0: \beta_1 = 0 against the alternative hypothesis: Ha:β10H_a: \beta_1 \neq 0

    Where β1\beta_1 is the slope of the regression line.

  2. Determine the degrees of freedom (df):

    • df for the numerator (df1_1): The number of predictor variables (in this case, 1).
    • df for the denominator (df2_2): Total observations (nn) minus the number of parameters estimated (2: the intercept and the slope), so n2n - 2.

    df1=1anddf2=n2=162=14df_1 = 1 \quad \text{and} \quad df_2 = n - 2 = 16 - 2 = 14

  3. Locate the F-statistic value: The F-statistic is given as F=42F = 42.

  4. Use an F-distribution table or software: Using the F-distribution with df1=1df_1 = 1 and df2=14df_2 = 14, the p-value for F=42F = 42 can be computed.

    We can use statistical software or a calculator to find the exact p-value. For large F-values, the p-value will typically be very small.

    Let's calculate this.from scipy.stats import f

Parameters

F_stat = 42 # F statistic df1 = 1 # Numerator degrees of freedom df2 = 14 # Denominator degrees of freedom

Calculate the p-value for the F statistic

p_value = 1 - f.cdf(F_stat, df1, df2) p_value1.4471306468033518e-051.4471306468033518e-05successThe p-value for the F-test is approximately 0.0000145. This indicates a very small probability of observing such a large F-statistic under the null hypothesis H0:β1=0H_0: \beta_1 = 0. Therefore, the regression slope is statistically significant.

Let me know if you'd like a further explanation or have questions about this result. Here are some related questions for practice:

  1. How is the F-statistic computed in a regression analysis?
  2. What does the p-value signify in the context of regression?
  3. How do you interpret the degrees of freedom in an F-test?
  4. Why is the null hypothesis H0:β1=0H_0: \beta_1 = 0 important in regression analysis?
  5. How would this test change if there were multiple predictor variables?

Tip: Always compare the p-value to the chosen significance level (e.g., α=0.05\alpha = 0.05) to determine whether to reject the null hypothesis.

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Math Problem Analysis

Mathematical Concepts

Regression Analysis
F-Test
Hypothesis Testing
p-value

Formulas

ŷ = b0 + b1x (Regression Line Equation)
F = (SSR / df1) / (SSE / df2) (F-statistic Formula)
Degrees of Freedom: df1 = k (predictors), df2 = n - k - 1
p-value = 1 - F.cdf(F-statistic, df1, df2)

Theorems

F-Distribution in Hypothesis Testing
Null Hypothesis Testing for Slope (H0: β1 = 0)

Suitable Grade Level

Undergraduate - Statistics