@article {Bix:September 2003:0894-3214:199, author = "Bix L.", author = "Lockhart H.", author = "Selke S.", author = "Cardoso F.", author = "Olejnik M.", title = "Is x-height a better indicator of legibility than type size for drug labels?", journal = "Packaging Technology and Science", volume = "16", year = "September 2003", abstract = "In 1999 the US Food and Drug Administration published a regulation in an attempt to ensure the legibility of OTC drugs, specifying, among other things, a minimum type size of 6 points. This is problematic because different typefaces of the same size vary widely in type heights and, presumably, legibility. We hypothesized that specifying a minimum x-height, the height of the lowercase x, would produce more consistent legibility than the minimum type size specified within the regulation.

Twenty-six subjects viewed two groups of typefaces using the Lockhart Legibility Instrument to quantify legibility. The first group contained typefaces that were all 6 points, but, by nature of their design, varied greatly in their x-heights. The second group was made from the same set of typefaces, but these were manipulated so that their x-heights were equal to the average x-height of group 1. A likelihood ratio test indicated that the group that varied in x-height, group 1, produced significantly more variable results than the group with equal x-heights, group 2. This indicates that specifying a minimum type size may not be the best approach for producing consistent legibility. Copyright © 2003 John Wiley & Sons, Ltd.", pages = "199-207(9)", url = "http://www.ingentaconnect.com/content/jws/pts/2003/00000016/00000005/art00003" doi = "doi:10.1002/pts.625" }