  Spreadsheets are known to be error-prone. Over the last decade, research has
been done to determine the causes of the high rate of errors in spreadsheets.
This paper examines the added value of a spreadsheet tool (PerfectXL) that
visualizes spreadsheet dependencies and determines possible errors in
spreadsheets by defining risk areas based on previous work. This paper will
firstly discuss the most common mistakes in spreadsheets. Then we will
summarize research on spreadsheet tools, focussing on the PerfectXL tool. To
determine the perceptions of the usefulness of a spreadsheet tool in general
and the PerfectXL tool in particular, we have shown the functionality of
PerfectXL to several auditors and have also interviewed them. The results of
these interviews indicate that spreadsheet tools support a more effective and
efficient audit of spreadsheets; the visualization feature in particular is
mentioned by the auditors as being highly supportive for their audit task,
whereas the risk feature was deemed of lesser value.
