Chapter 6 215 Figure 9 Break stress of hair according to ethnicity mean ± confidence intervals at 95% ethnic groups with the same letter designation are statistically the same results are from 428 subjects and 21,400 fibers. Figure 10 Cross-sectional area of hair as a function of ethnicity mean ± confidence intervals at 95% ethnic groups with the same letter designation are statistically the same results are from 428 subjects and 21,400 fibers.