Find How many data points were used in this model developmen

Find How many data points were used in this model development? Which variable (other than intercept) would you throw out next? Why? Is this a better model than the \"mean\" model, explain your rationale

Solution

a. Let total number of observation be x

Then total degrees of freedom x-1

No of covariates is 6

Hence degrees of freedom of error is x-1-6=493 i.e x=500

So total number of observation is 500

b. The covariate x3 needs to be droppped as its coefficient has the largest p value. Hence it is insignificant

c. It is better than the mean model as the coefficients corresponding to the covariates X7,X9 AND X11 is highly significant