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FRM Part I · FRM Exam Part I · Regression with Multiple Explanatory Variables

A model of credit spreads is first estimated with 3 explanatory variables on 60 observations, giving a residual sum of squares (RSS) of 48. Adding 2 further variables lowers RSS to 40. Testing whether the 2 added coefficients are jointly zero, the F-statistic is closest to which value?

The F-statistic is about 5.4, closest to 5.5. It equals the reduction in residual sum of squares per restriction, (48-40)/2 = 4, divided by the unrestricted residual variance, 40/54 = 0.741, where 54 is 60 observations minus 6 estimated coefficients.

  1. A5.5Correct
  2. B4.0
  3. C6.6
  4. D2.2

Explanation

Restricted model: 3 variables plus intercept. Unrestricted has 5 variables plus intercept, so df = 60-6 = 54. F = [(48-40)/2]/[40/54] = 4/0.7407 = 5.4, about 5.5. Using 56 df or other mistakes gives other values; 4.0 omits the denominator scaling.

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