242 
Fishery Bulletin 108(2) 
Table 3 
Summary statistics of meat weights and meat weight measurement errors (g) for Atlantic sea scallop (Placopecten magellanicus) 
shell-height measurements in experiment 2 (sample sizes are the same as those for shell-height measurements in Table 2). The 
original shell heights were obtained with calipers, video camera, and measure boards. “NA” means that a statistic is not applicable. 
Statistic 
True (calipers) 
Video 
Measuring boards 
Meat weights and measurement errors 
Bias 
NA 
-3.2 
-0.4 
Meat weights 
Minimum 
0.8 
0.5 
0.7 
5% quantile 
2.4 
1.7 
2.1 
95% quantile 
61.3 
58.3 
58.6 
Maximum 
136.9 
157.7 
138.0 
Average 
29.8 
27.3 
29.4 
Percent bias 
NA 
-10% 
-1% 
Standard deviation 
22.2 
21.4 
21.8 
Coefficient of deviation 
74% 
78% 
74% 
Square root of the mean squared error 
NA 
21.6 
21.8 
Percent square root of the mean squared error 
NA 
71% 
74% 
Skewness (g x ) 
0.99 
1.53 
0.92 
Kurtosis (g 2 ) 
3.00 
6.22 
2.61 
Measurement errors 
Standard deviation 
NA 
5.1 
1.5 
Square root of the mean squared error 
NA 
6.0 
1.6 
Skewness (g^) 
NA 
-0.80 
-1.06 
Kurtosis ( g 2 ) 
NA 
2.48 
4.68 
Table 4 
Estimated probability distributions for Atlantic sea scallop ( Placopecten magellanicus) shell-height (SH) measurements based on 
bias and standard deviations from experiment 2. Condition factors for error matrices used in the catch-at-size-analysis (CASA) 
stock assessment model scenarios are given also. The shell-height bins are 5-mm wide and identified by their midpoint. For 
example, sea scallops 80-84.9 mm SH fall into a bin whose midpoint is 82.5 mm. 
Video scenario 
Measuring board scenario 
Calipers 
Imprecision 
Imprecision 
Imprecision 
Imprecision 
Statistic (true shell height) 
Bias only 
only 
and bias 
Bias only 
only 
and bias 
Condition factor (k) 
NA 
3xl0 15 
5457 
2638 
1.6 
2.1 
2.3 
Bias (mm) 
0 
-4.5 
0 
-4.5 
-0.6 
0 
-0.6 
Standard deviation (mm) 
0 
0 
6.1 
6.1 
0 
1.7 
1.7 
Shell height bin (mm) 
Probability of observed bins 
72.5 
77.5 
0.0009 
82.5 
0.0014 
0.0167 
87.5 
0.0203 
0.0820 
92.5 
0.0929 
0.2158 
0.0001 
97.5 
0.8000 
0.2300 
0.3101 
0.2000 
0.1325 
0.2008 
102.5 
1.0000 
0.2000 
0.3110 
0.2436 
0.8000 
0.7349 
0.7181 
107.5 
0.2300 
0.1045 
0.1325 
0.0810 
112.5 
0.0929 
0.0243 
117.5 
0.0203 
0.0020 
122.5 
0.0014 
127.5 
