Preference for and understanding of graphs presenting health risk information. The role of age, health literacy, numeracy and graph literacy

Objective To investigate 1) younger (< 65) and older (> 65) adults’ preference for and understanding of graph formats presenting risk information, and 2) the contribution of age, health literacy, numeracy and graph literacy in understanding information. Materials and methods To assess preferences, participants (n = 219 < 65 and n = 227>65) were exposed to a storyboard presenting six types of graphs. Understanding (verbatim and gist knowledge) was assessed in an experiment using a 6 (graphs: clock, bar, sparkplug, table, pie vs pictograph) by 2 (age: younger [<65] vs older [>65]) between-subjects design. Results Most participants preferred clock, pie or bar chart. Pie was not well understood by both younger and older people, and clock not by older people. Bar was fairly well understood in both groups. Table yielded high knowledge scores, particularly in the older group. Lower age, higher numeracy and higher graph literacy contributed to higher verbatim knowledge scores. Higher health literacy and graph literacy were associated with higher gist knowledge. Discussion and conclusion Although not the preferred format, tables are best understood by older adults. Practice implications Graph literacy skills are essential for both verbatim and gist understanding, and are important to take into account when developing risk information.