I'm trying to replicate this table from this website (without AIC included): <https://uc-r.github.io/model_selection>

I think I've got most of it down, however, I'd like so the brackets increase in size so that that they have the full length of `1/n` for `Cp` and `BIC`. For the `Adjusted R^2`, I'd like the bracket to extend to around the entire fraction. Also I'd like the column height to become a bit greater as it is looking a bit squashed at the moment.

[![enter image description here](https://i.stack.imgur.com/hUbsV.png)](https://i.stack.imgur.com/hUbsV.png)

```
\documentclass[11pt,a4paper,titlepage]{article}
\usepackage[a4paper]{geometry}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{lipsum}
\usepackage{amsmath}
\usepackage{booktabs}
\usepackage[allow-number-unit-breaks]{siunitx}
\usepackage[flushleft]{threeparttable}
\usepackage{graphicx}

\begin{table}[!htbp] \centering 
\caption{Summary Model Statistics for Multiple Linear Regression Model} 
\label{tab5} 
\begin{tabular}{@{\extracolsep{5pt}}lll} 
\\[-1.8ex]\toprule 
\\[-1.8ex] 
Statistic & \multicolumn{1}{c}{Objective} & \multicolumn{1}{c}{Equation} \\
\midrule \\[-1.8ex]
$C_p$ & Minimise & $C_p$ = $\frac{1}{n}$ $(RSS + 2d\hat{\sigma})$ \\
Bayesian Information Criterion (BIC) & Minimise & $BIC$ = $\frac{1}{n}$ $(RSS + log(n)d\hat{\sigma}^2)$ \\
Adjusted $R^2$ & Maximise & Adj. $R^2$ = $1 - (\frac{RSS/n-d-1}{TSS/(n-1)})$  \\
\bottomrule \\[-1.8ex] 
\end{tabular} 
\end{table} 

```