</a></h2>
    <p>dataframe with the following columns:</p><dl><dt><strong>study_id</strong></dt>
<dd><p>study identification</p></dd>
 <dt><strong>site_number</strong></dt>
<dd><p>site
identification</p></dd>
 <dt><strong>n_pat</strong></dt>
<dd><p>number of patients, site level</p></dd>

<dt><strong>visit_med75</strong></dt>
<dd><p>adjusted median(max(visit)) * 0.75 see Details</p></dd>

<dt><strong>n_pat_with_med75</strong></dt>
<dd><p>number of patients that meet visit_med75
criterion, site level</p></dd