'><a href='https://rdrr.io/r/base/data.frame.html'>data.frame</a></span><span class='op'>(</span>STUDYID <span class='op'>=</span> <span class='fl'>1</span><span class='op'>:</span><span class='fl'>5</span>, USUBJID <span class='op'>=</span> <span class='va'>LETTERS</span><span class='op'>[</span><span class='fl'>1</span><span class='op'>:</span><span class='fl'>5</span><span class='op'>]</span>,
                 LBDTC <span class='op'>=</span> <span class='fu'><a href='https://rdrr.io/r/base/rep.html'>rep<