We have a partnership arrangement with another site where we pay them for users sent to us. However, they claim our referral numbers for them are lower than theirs by 50%. They are tracking clicks in Google Analytics (using events) while we are using visits in Google Analytics.

Are we doing something wrong with our Google Analytics installation?

<!-- Google Analytics BEGIN -->
<script type="text/javascript">
  var _gaq = _gaq || [];
  _gaq.push(['_setAccount', 'UA-12345678-1']);
  _gaq.push(['_setDomainName', 'example.com']);
  _gaq.push(['_trackPageview']);

  (function() {
    var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
    ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
  })();
</script>
<!-- Google Analytics END -->