Problem with aligning numbers with brackets surrounding them

Question

english is not my native language, but I will try to explain my question the best way I can.

My problem is the extra spacing between the L and T column which apparently comes when I write the numbers in scientific mode. Is there any way to have scientific numbers like this, align them on comma, and make the spacing in columns more normal (smaller) ?

Preamble:

\documentclass[12pt,twoside]{report}
\usepackage{booktabs}
\usepackage{siunitx}
\usepackage[a4paper,width=150mm,top=25mm,bindingoffset=6mm]{geometry}
\usepackage{amsmath}
\sisetup{input-symbols = ()}

Table code:

\begin{table}[ht]\centering
\caption[caption]{caption}\label{reg_basis1}
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\sisetup{table-space-text-post = \sym{***}}

\begin{tabular}{l*{5}{S[table-align-text-post=false]}}
\toprule
\multicolumn{1}{l}{\textbf{}}&\multicolumn{1}{c}{\textbf{L}}&
\multicolumn{1}{c}{\textbf{T}}&\multicolumn{1}{c}{\textbf{n}}&
\multicolumn{1}{c}{\textbf{\(R^{2}\)}}&
\multicolumn{1}{c}{\textbf{Justert $R^{2}$}}\\
\midrule
1997 - 2008 & 0.207 \sym{***} & 3.5\num{1e-4} \sym{***} & {623} & 0.27 & 0.21  \\
            & (0.049)         & (0.8\num{1e-4})         &       &      &       \\
        \addlinespace
2009 - 2015 &&&&&  \\
            &&&&&  \\
        \addlinespace
\bottomrule
\multicolumn{5}{l}{\footnotesize Estimerte standardavvik er gitt i parenteser}\\
\multicolumn{5}{l}{\footnotesize \sym{*} $p<0.05$, \sym{**} $p<0.01$, \sym{***} \  $p<0.001$}\\
\end{tabular}
\end{table}

I hope anyone here has time to answer me. I have tried searching/googling, but I haven't found anything specific which I can use to solve my problem.

Answer 1

I think your main problem are the (round) brackets used to surround your numbers, because they are also used as natural input of the \num command to indicate the error of a number. That is why you have to protect the (round) brackets by putting them into curly brackets.

(I wouldn't use your solution and add them to the input-symbols, because that could cause some undesired side effects, which I haven't tested for.)

To then get the spacing right is pretty straight forward and is already answered for example here providing the "elements" which could be found in the column to the options of the S specifier like table-format. (Have a look at table 25 of the siunitx manual v2.6 on page 47).

Have a look at the following code which I reduced a little bit, to not distract from the main tabular.

\documentclass[border=2mm]{standalone}
\usepackage{amsmath}
\usepackage{booktabs}
\usepackage{siunitx}
\begin{document}
        \def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
        \sisetup{
            table-align-text-post=false,
        }
    \begin{tabular}{
        l
        S[table-format=1.3,   table-space-text-pre={(},table-space-text-post={\sym{***}}]
        S[table-format=1.1e-1,table-space-text-pre={(},table-space-text-post={\sym{***}}]
        S[table-format=3]
        S[table-format=1.2]
        S[table-format=1.2]
        }
            \toprule
                      & {\textbf{L}}    & {\textbf{T}}   & {\textbf{n}}
                                                               & {\textbf{$R^{2}$}}
                                                                      & {\textbf{Justert $R^{2}$}} \\
            \midrule
        1997 -- 2008  & 0.207 \sym{***} & 3e-4 \sym{***} & 623 & 0.27 & 0.21 \\
                      & {(}0.049{)}     & {(}0.8e-4{)}   &     &      &      \\
                \addlinespace
        2009 -- 2015  &                 &                &     &      &      \\
                      &                 &                &     &      &      \\
                \addlinespace
            \bottomrule
        \multicolumn{5}{l}{\footnotesize Estimerte standardavvik er gitt i parenteser}\\
        \multicolumn{5}{l}{\footnotesize
            \sym{*}   $p < \num{0.05}$,
            \sym{**}  $p < \num{0.01}$,
            \sym{***} $p < \num{0.001}$}\\
    \end{tabular}
\end{document}