  Spreadsheet users regularly deal with uncertainty in their data, for example
due to errors and estimates. While an insight into data uncertainty can help in
making better informed decisions, prior research suggests that people often use
informal heuristics to reason with probabilities, which leads to incorrect
conclusions. Moreover, people often ignore or simplify uncertainty. To
understand how people currently encounter and deal with uncertainty in
spreadsheets, we conducted an interview study with 11 spreadsheet users from a
range of domains. We found that how people deal with uncertainty is influenced
by the role the spreadsheet plays in people's work and the user's aims.
Spreadsheets are used as a database, template, calculation tool, notepad and
exploration tool. In doing so, participants' aims were to compute and compare
different scenarios, understand something about the nature of the uncertainty
in their situation, and translate the complexity of data uncertainty into
simplified presentations to other people, usually decision-makers. Spreadsheets
currently provide limited tools to support these aims, and participants had
various workarounds.
