Results of all QA/QC Exercises
for Surfclam, Spisula solidissima

Spisula solidissima


Nina Shepherd (NS) has been working with Atlantic Surfclam since 2018; before that, the age reader was Blanche Jackson (BJ, retired). A section is taken from the hinge of the shell and viewed with reflected light.

In tests where agreement is below 90%, bias indicates either the P-value of a Bowker’s test or ‘n/s’ (test not significant at the α = 0.05 level).

Sample Source Test Type Date Completed Age Reader Number Aged Number Tested CV (%) Agreement (%) Bias
2015 Clam Survey (201560) Precision 12/2015 BJ 717 100 0.26 94.0  
2012 Clam Survey (201260) Precision 11/2015 BJ 328 70 0.09 97.1  
2013 Clam Survey (201360) Precision 8/2015 BJ 94 35 0.29 94.3  
2011 Clam Survey (201104) Precision 10/2012 BJ 444 95 2.25 72.6 n/s
2008 Clam Survey (200808) Precision 10/2008 BJ 840 100 3.13 76.0 n/s
2005 Clam Survey (200507) Precision 8/2005 BJ 889 141 3.43 65.2 n/s
2002 Clam Survey (200206) Calibration 6/2005 BJ -- 609 1.75 84.2 n/s

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