Not enough space in table for fractions

Question

The table that I'd like to make does not display fractions with enough space between lines. What's the reasoning for this? (Not enough rep to be able to post a picture yet unfortunately.)

\documentclass{article}
\usepackage{amsmath,amsfonts}
\usepackage{booktabs}

\begin{document}
\begin{table}
\centering
\begin{tabular}{lcccc}
\toprule
\textbf{Care type} & $\mathbb{P}(Pat \cap H)$ & $\mathbb{P}(Pat \cap H')$ & $\mathbb{P}(Pat' \cap H)$ & $\mathbb{P}(Pat' \cap H')$\\
\midrule
Direct care  &$\displaystyle \dfrac{58}{197}$  &  $\displaystyle \dfrac{48}{197}$  & $\displaystyle \dfrac{21}{197}$* &$1-\displaystyle \dfrac{58}{197}$ \\
Housekeeping &$\displaystyle \dfrac{12}{17}$  &  $\displaystyle \dfrac{2}{17}$  & $\displaystyle \dfrac{5}{17}$* &$1-\displaystyle \dfrac{12}{17}$\\
\bottomrule
\end{tabular}
\caption{Probabilities of hand hygiene given direct patient contact}
\label{tab:handwash_given_pat}
\end{table}
\end{document}

Edit: Image added and MWE completed.

Answer 1

Manually the spacing can be fixed by several methods:

• \renewcommand*{\arraystretch}{2} (see Herbert's comment)
  However, this also affects the spacing of the other lines.

• Adding a vertical space in the optional argument of \\, e.g.:

  \begin{tabular}{...}
    ...
    ...\\[2ex]
    ...\\[1.5ex]
    \bottomrule
  \end{tabular}
  

• Adding an invisible rule in the line, e.g.:

  \begin{tabular}{...}
    ...
    \rule{0pt}{3.5ex}Direct care ...\\
    \rule[-2.5ex]{0pt}{7ex}Housekeeping ...\\
    \bottomrule
  \end{tabular}
  

Answer 2

I'll add three other methods.

First, since you load booktabs, you can add \addlinespace between the second and third rows.

Second, you can use the cellspace package, which enables you to define minimal vertical spacings at the top and bottom of cells in columns with specifier prefixed with the letter S (or C if you use siunitx). This way, the contents is vertically centred in the cell, contrary to the use of \arraystretch.

Last, the makecell package, through its \setcellgapes and \makegapedcells commands, adds vertical spacing at the top and bottom of every cell. This can also be done for individual cells with the \Gaped command.

\documentclass{article}
\usepackage{amsmath,amsfonts}
\usepackage{booktabs}
\usepackage{cellspace}%
\setlength\cellspacetoplimit{3pt}
\setlength\cellspacebottomlimit{3pt}
\usepackage{makecell}
\setcellgapes{3pt}

\begin{document}

\begin{table}[!htbp]
  \centering
  \begin{tabular}{l*{4}{>{$}c<{$}}}
    \toprule
    \textbf{Care type} & \mathbb{P}(Pat ∩ H) & \mathbb{P}(Pat ∩ H') &  \mathbb{P}(Pat' ∩ H) & \mathbb{P}(Pat' ∩ H')  \\ \midrule
    Direct care & \dfrac{58}{197} & \dfrac{48}{197} & \dfrac{21}{197} * & 1-\dfrac{58}{197}  \\\addlinespace%
    Housekeeping & \dfrac{12}{17} & \dfrac{2}{17} &\dfrac{5}{17}* &  1- \dfrac{12}{17} \\ \bottomrule
  \end{tabular}
  \caption{Probabilities of hand hygiene given direct patient contact}
  \label{tab:handwash_given_pat}
\end{table}

\begin{table}[!htbp]
  \centering
  \begin{tabular}{l*{4}{>{$}Sc<{$}}}
    \toprule
    \textbf{Care type} &  \mathbb{P}(Pat ∩ H)$ & \mathbb{P}(Pat ∩ H') & \mathbb{P}(Pat' ∩ H)  &  \mathbb{P}(Pat' ∩ H') \\ \midrule
    Direct care & \dfrac{58}{197} & \dfrac{48}{197} & \dfrac{21}{197}* &  1-\dfrac{58}{197} \\%
    Housekeeping & \dfrac{12}{17} & \dfrac{2}{17} & \dfrac{5}{17}* &  1-\dfrac{12}{17} \\ \bottomrule
  \end{tabular}
  \caption{Probabilities of hand hygiene given direct patient contact}
  \label{tab:handwash_given_pat}
\end{table}

\begin{table}[!htbp]
  \centering\makegapedcells
  \begin{tabular}{l*{4}{c}}
    \toprule
    \textbf{Care type} & mathbb{P}(Pat ∩ H) & \mathbb{P}(Pat ∩ H') & \mathbb{P}(Pat' ∩ H) & \mathbb{P}(Pat' ∩ H') \\ \midrule
    Direct care & \dfrac{58}{197} & \dfrac{48}{197} & \dfrac{21}{197}$* & 1-\dfrac{58}{197} \\%
    Housekeeping & \dfrac{12}{17} &\dfrac{2}{17} & \dfrac{5}{17}$* & 1-\dfrac{12}{17} \\ \bottomrule
  \end{tabular}
  \caption{Probabilities of hand hygiene given direct patient contact}
  \label{tab:handwash_given_pat}
\end{table}

\end{document} 

Answer 3

Another option is to use the package units and then replace your \frac{a}{b} with \nicefrac{a}{b}. The numerator and denominator will be offset diagonally and they fit nicely into tables.

Answer 4

With {NiceTabular} of nicematrix, you have two keys cell-space-top-limit and cell-space-bottom-limit which sets the minimal space above and below the cells of the tabular. There is also a key cell-space-limits which is the conjunction of these keys.

\documentclass{article}
\usepackage{amsmath,amsfonts}
\usepackage{booktabs,nicematrix}
\begin{document}
\begin{table}
\centering
\begin{NiceTabular}{lcccc}[cell-space-limits=2pt]
\toprule
\textbf{Care type} & $\mathbb{P}(Pat \cap H)$ & $\mathbb{P}(Pat \cap H')$ & $\mathbb{P}(Pat' \cap H)$ & $\mathbb{P}(Pat' \cap H')$\
\midrule
Direct care  &$\displaystyle \dfrac{58}{197}$  &  $\displaystyle \dfrac{48}{197}$  & $\displaystyle \dfrac{21}{197}$* &$1-\displaystyle \dfrac{58}{197}$ \
Housekeeping &$\displaystyle \dfrac{12}{17}$  &  $\displaystyle \dfrac{2}{17}$  & $\displaystyle \dfrac{5}{17}$* &$1-\displaystyle \dfrac{12}{17}$\
\bottomrule
\end{NiceTabular}
\caption{Probabilities of hand hygiene given direct patient contact}
\label{tab:handwash_given_pat}
\end{table}
\end{document}

You need several compilations (because nicematrix uses PGF/Tikz nodes under the hood).

Answer 5

For me, $\displaystyle \dfrac{\mathstrut 58}{\mathstrut 197}$ works well in cases in which I do only have a small number of elements. For more information about \mathstrut and friends, see here.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{tabular}{|l|}
    \hline
    $\dfrac{100}{30}$\
    \hline
    $\dfrac{\mathstrut 100}{30}$\
    \hline
    $\dfrac{\mathstrut 100}{\mathstrut 30}$\
    \hline

\end{tabular}
\end{document}