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Fishery Bulletin 108(2) 
45 
40 - 
35 - 
30 - 
25 
20 - 
15 - 
10 - 
5 
0 
d 
k 
0 
10 20 30 
Band count reader 1 
40 
Band count reader 1 
45 
40 
35 
30 - 
25 - 
20 
15 
10 - 
5 - 
0 
3 
0 
10 20 30 
Band count reader 3 
40 
Band count reader 3 
Figure 3 
A comparison of age counts among readers. (A) Reader 2’s mean band counts (y-axis) in 
relation to the band counts of reader 1; (B) Reader 3’s mean band counts in relation to 
the band counts of reader 1; and (C) Reader 2’s mean band counts in relation to the band 
counts of reader 3. Vertical lines are 95% confidence intervals and the diagonal line is 
the 1:1 relationship line. (D) Percent agreement and coefficient of variation for reader 2 
(Rd 2) compared to reader 1. The percent agreement (±10%) is represented by the solid 
line and circles and the coefficient of variation (CV) by the dashed line and open circles. 
(E) Percent agreement and coefficient of variation of reader 3 (Rd 3) compared to reader 
1; and (F) Percent agreement and coefficient of variation of reader 2 (Rd 2) compared to 
those of reader 3. 
of any of the data groupings (P>0.99, 0.019<x 2 <4.525). 
Thus, we failed to find evidence of sampling bias or 
geographic differences in average size at age. 
Age determinations 
Sampled dogfish ranged in age from 8 to 50 years old. 
The x 2 test and the age-bias plots indicated no signifi- 
cant systematic bias between the three readers (x 2 =241, 
206, and 259 between readers 2 and 1, readers 2 and 
3, and readers 3 and 1, respectively; all P>0.05; Fig. 
3, A-C). The percent agreement between readers 2 
and 1 (Fig. 3D) and readers 3 and 1 (Fig. 3E) was high 
for band counts less than 30 but was more variable 
or decreased for band counts greater than 30 (Fig. 3, 
D-F). For readers 2 and 3, the percent agreement was 
