1. An experiment was conducted in order to study the size of squid eaten by sharks and tuna. The predictor variables are characteristic of the beak or mouth of the squid. The predictors and response considered for the study are: I1 : Rostral length in inches 2 : Wing length in inches I; : Rostral to notch length I, : Notch to wing length $5 : Width in inches y : Weight in pounds The study involved measurements and weight taken on 22 specimen and is available in the squid. txt data set. (I) Best subset selection. Carry out a best subset linear regression analysis using the regsubsets () function on the squid data set. (a) Copy summary output in your report and briefly comment on the models identified in this output. From the summary ouput, identify the best model obtained with the four predictors. (b) What is the best model based on adjusted RY, PRESS and Cp from among the chosen models by the regsubsets () function? To provide evidence for your answer, include in your report a Lable showing the values of adjusted RY, PRESS and Cp for the best subsets of each size. Include also two plots, one of adjusted R and another of Cp for the best subsets of each size against the number of predictors. (II) Sequential variable selection on the squid data set. (a) Carry out forward model selection with the stepAICO) function, using all the available predictors and starting from the model with just an intercept. (1) Copy the R output in your report and describe the selection procedure from the output. At each step state the 'current model', which predictor was added to the current model and why. (il) Clearly state the final model obtained, including the coefficient estimates of the fitted model. How does your answer compare to the results in (1)? (b) Repeat a) using back ward model selection, starting from the model with all the available predictors