Report the Error Degrees of Freedom for this example Assume

Report the Error Degrees of Freedom for this example:

Assume you have 150 observations:

You decide to create a model that relates the response to three explanatory variables, such that one of them is categorical with 2 levels, one of them has a linear relationship with the response, and one of them has a quadratic relationship to the response.

What are the Error Degrees of Freedom?

Solution

Number of explanatory variables(k) = 3

Sample size(n) = 150

Error degrees of freedom = Sample size - Number of parameters estimated

Number of parameters estimated = k + 1

(1 parameter1 for each explanatory variable and 1 parameter for intercept)

So,

Error degrees of freedom = n - (k+1) = 150 - 4 = 146