Examples enumerated in the margins

Question

I am writing a paper about phonetics that contains lots of examples, usually organised in tables. What I would like is to have these examples enumerated in the margins. Specifically, I need an environment called example, so that whatever I write

\begin{example}
    some examples
\end{example}

LaTeX prints this text along with a margin note saying, e.g., "Example 2.7". It is supposed to work a bit like in this book.

I did try with the following code:

\newenvironment{example}
{
    \marginpar{\begin{center}Examples\\ \refstepcounter{examples}\theexamples\end{center}}
    \medskip\begin{center}
}
{
    \end{center}\medskip
}

but the numbers are not always aligned correctly with the examples in the margins.

Any good ideas about how to make this? :-)

UPDATE: On request from cmhughes, I now add my entire preamble so that he may see the problem. :-)

\documentclass[a4paper]{memoir}

%Memoir settings
\setlrmarginsandblock{*}{3.5cm}{0.75}
\setulmarginsandblock{3cm}{*}{1.2}
\checkandfixthelayout[nearest]

\usepackage{amsmath,amssymb,geometry,graphicx,amstext,enumerate,multirow,color,multicol,comment,xcolor}
\usepackage[hidelinks]{hyperref}
\usepackage{cleveref}
\usepackage[ansinew]{inputenc}
\usepackage{wasysym}
\usepackage{tipa,vowel,textcomp}


\chapterstyle{veelo}
\pagestyle{headings}

\usepackage[amsmath]{ntheorem}      % for theorem-like environments

% margin theorem
\makeatletter
\newtheoremstyle{mymargin}%
{\item[\theorem@headerfont \llap{##1 ##2}]}%
{\item[\theorem@headerfont \llap{##1 ##2}| ##3\theorem@separator\hskip\labelsep]}%
\makeatother

% my example
\theoremstyle{mymargin}
\theorembodyfont{}      % customize these to suit your tastes
\theoremsymbol{}
\theoremprework{}
\theorempostwork{}
\theoremseparator{}
\newtheorem{example}{example}
\numberwithin{example}{section}
%\usepackage{subcaption}

\begin{document}

However, using this preamble resulted in the example enumeration looking like this:

See, the number appears to the right of the margin.

Do you have an idea what the problem may be? :-)

Answer 1

There's a few ways that you can do this. Personally, I favour the ntheorem package

I have loaded the geometry package with showframe=true just to highlight the page boundary, and lipsum just for sample text.

\documentclass{report}

\usepackage[showframe=true]{geometry}
\usepackage{lipsum}                 % for sample text
\usepackage{amsmath}
\usepackage[amsmath]{ntheorem}      % for theorem-like environments

% margin theorem
\makeatletter
\newtheoremstyle{mymargin}%
{\item[\theorem@headerfont \llap{##1 ##2}]}%
{\item[\theorem@headerfont \llap{##1 ##2}| ##3\theorem@separator\hskip\labelsep]}%
\makeatother

% my example
\theoremstyle{mymargin}
\theorembodyfont{}      % customize these to suit your tastes
\theoremsymbol{}
\theoremprework{}
\theorempostwork{}
\theoremseparator{}
\newtheorem{myexample}{example}
\numberwithin{myexample}{section}

\begin{document}

\begin{myexample}
\lipsum[2]
\end{myexample}
\end{document}

You could achieve the same output by using a simple list, using the enumitem package, but I think a theorem package is most appropriate here.