Graphs are frequently used as decision aids. When properly designed, graphs facilitate decision making by highlighting important trends and relationships in the data. It is all too easy, however, to design graphs so that they do not accurately portray the underlying data (Tufte 1983). Indeed, there is considerable evidence that annual reports contain such improperly designed graphs (Beattie and Jones 1992a, 1992b; Courtis 1997; Johnson et al. 1980; Jones and Beattie 1997; Steinbart 1989). This paper reports the results of three experiments that investigated the effects of such improperly designed graphs on subjects' choices. The results of all three experiments show that improperly designed graphs can alter subjects' choices. These findings not only have important implications for the design and use of graphs as decision aids, but also raise potential policy issues.
