Problem with `statsoc` class and pdflatex

Add \usepackage[a4paper]{geometry} as line 2 of your .tex file and the file will render correctly.

\documentclass{statsoc}
\usepackage[a4paper]{geometry}

\usepackage[utf8]{inputenc}
\usepackage{lipsum}

\usepackage{amsmath,amssymb}
\usepackage{natbib}

\title[Short title]{Long title}
\author[author short]{author long}


\begin{document}

\begin{abstract}
\lipsum
\end{abstract}

\keywords{keyword1 \and keyword2}

\end{document}

The class sets a different page size, namely width 17.3cm and height 24.7cm (actually 41pc and 58.5pc respectively), but doesn't pass correctly the parameters the PDF driver.

\documentclass{statsoc}

\usepackage{geometry}

\geometry{
  textwidth=33pc,
  textheight=\dimexpr48\baselineskip+\topskip\relax,
  marginparsep=11pt,
  marginparwidth=107pt,
  footnotesep=6.65pt,
  headheight=9pt,
  headsep=9pt,
  footskip=30pt,
}

\usepackage[utf8]{inputenc}
\usepackage{lipsum}

\usepackage{amsmath,amssymb}
\usepackage{natbib}

\title[Short title]{Long title}
\author[author short]{author long}


\begin{document}

\begin{abstract}
\lipsum
\end{abstract}

\keywords{keyword1 \and keyword2}

\end{document}

If you want to impose it on A4 paper,

\documentclass{statsoc}

\usepackage[a4paper]{geometry}

\geometry{
  layoutheight=58.5pc,
  layoutwidth=41pc,
  textwidth=33pc,
  textheight=\dimexpr48\baselineskip+\topskip\relax,
  marginparsep=11pt,
  marginparwidth=107pt,
  footnotesep=6.65pt,
  headheight=9pt,
  headsep=9pt,
  footskip=30pt,
}

\usepackage[utf8]{inputenc}
\usepackage{lipsum}

\usepackage{amsmath,amssymb}
\usepackage{natbib}

\title[Short title]{Long title}
\author[author short]{author long}


\begin{document}

\begin{abstract}
\lipsum
\end{abstract}

\keywords{keyword1 \and keyword2}

\end{document}