using width and height I can make the graph bigger, however if it is made too big the graph will start to shift towards the right and bottem of the page, despite there being plenty of space left on the page up in the top and left of the page. How can I force the graph to always remain in the center (both vertically and horizontally) of the page and not shift itself when its made bigger.
\begin{tikzpicture}[rotate=90]
\begin{axis}
[
width=24cm, height=17cm,
title={},
xlabel={},
ylabel={},
minor grid style = dashed,
major grid style = draw,
minor tick num = 1,
grid = both,
mark size = 1,
]
\addplot[scatter,mark=square*,mark size=2,only marks]
table{data.dat};
\addplot[thick,red]
table[y={create col/linear regression={y=Y}}]{data.dat};
\end{axis}
\end{tikzpicture}

tikzpictureinside\begin{center} ... \end{center}? – alexkelbo Mar 12 '16 at 14:44