# Question: In regression modeling for t tests about regression parameters df

In regression modeling, for t tests about regression parameters, df = n - number of parameters in equation for the mean.

a. Explain why df = n - 2 for the model μy = α + βx.

b. Chapter 8 discussed how to estimate a single mean μ. Treating this as the parameter in a simpler regression model, μy = μ, with a single parameter, explain why df = n - 1 for inference about a single mean.

a. Explain why df = n - 2 for the model μy = α + βx.

b. Chapter 8 discussed how to estimate a single mean μ. Treating this as the parameter in a simpler regression model, μy = μ, with a single parameter, explain why df = n - 1 for inference about a single mean.

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