/code> is <em>not</em> a formula. The vector identifying
the periods (pre/post) of the observations (the vector can be of any type but
must contain only two possible values). The first value (in the sorted sense)
of the vector is taken as the pre period. Must be of the same length as the data.</p></dd>


<dt id="arg-tex">tex<a class="anchor" aria-label="anchor" href="#arg-tex"></a></dt>
<dd><p>Should the result be displayed in Latex? Default is <code>FALSE</code>. Automatically
set to <code>TRUE</code> if t