Graphics, Figures & Tables ⇒ table with two LHS columns for independent variables - how to plot

[em4321]

Hi everyone,

I'm trying to plot this graph in overleaf and have been using the following code:

\begin{table}
\caption{Statistical analysis of data}
\centering
\label{table:statsoverview_table}
\begin{tabular}{c c c c c c}
\toprule
%\multirow{4}{*}{Scan Rate/mms}
\column{Direction of change}
\multicolumn{4}{c}{Power/mW} \\
\cmidrule{3-6}
& & 15 & 17 & 19 & 21 \\
\midrule
75 &increase& 63.6 & 83.3 & 91.7 & 90.9 \\
&decrease\\
25 &increase& 27.3 & 38.5 & 57.1 & 25.0 \\
&decrease\\
\bottomrule
\end{tabular}
\end{table}


But the format is not right as you can see. Does anyone have any suggestions? The issue with my table is that I have 3 independent variables and I need to add 2 columns on the LHS with different numbers of rows.