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:
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Understand the F-test setup: The F-statistic in this context is used to test the null hypothesis: against the alternative hypothesis:
Where is the slope of the regression line.
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Determine the degrees of freedom (df):
- df for the numerator (df): The number of predictor variables (in this case, 1).
- df for the denominator (df): Total observations () minus the number of parameters estimated (2: the intercept and the slope), so .
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Locate the F-statistic value: The F-statistic is given as .
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Use an F-distribution table or software: Using the F-distribution with and , the p-value for 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 . 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:
- How is the F-statistic computed in a regression analysis?
- What does the p-value signify in the context of regression?
- How do you interpret the degrees of freedom in an F-test?
- Why is the null hypothesis important in regression analysis?
- How would this test change if there were multiple predictor variables?
Tip: Always compare the p-value to the chosen significance level (e.g., ) 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