var do_show = 0;

function show_hide_column()
{
  var stl;

  if (do_show)
    { stl = '';
      document.getElementById("HideSE").innerHTML="Hide Standard Error"; 
      do_show = 0; // false
    } // if
  else
    { stl = 'none';
      document.getElementById("HideSE").innerHTML="Show Standard Error";
      do_show = 1; // true
    } // else

  var tbl=document.getElementById('PCPTable'); //returns unique element
  var rows=tbl.getElementsByTagName('tr'); // returns array of all "tr" elements

  var celsth=rows[0].getElementsByTagName('th')  //returns array of "th" in "tr"
  celsth[2].style.display=stl;  // Hide "Standard Error" heading

  for (var row=1;row<rows.length;row++) // Hide standard error data
  {
    var cels=rows[row].getElementsByTagName('td')  //returns array of "td" in "tr"
    cels[2].style.display=stl;
  } // for


} //function show_hide_column