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Marine research at CNR2005 2006Sensitivity 0.91 (0.035) 0.81 (0.07)Specificity 0.75 (0.13) 0.88 (0.11)Kappa 0.62 (0.12) 0.61 (0.13)AUC 83.4% (0.067) 85% (0.06)Table 2: Values of sensitivity, specificity and Area Under the Curve (AUC).Figure 3: 2005 and 2006 Receiver Operating Characteristic (ROC) plot.Variations of S and B are related to thenumber of POF 0; the lower the numberof POF youngest class, the better the variationsof S and B calculated using the twomethods (Tables 1 and 3). The lower S estimationsare in 1998 (both method); thehigher in 2001 (both method; Table 3).The stock biomass shows a large variabilityamong the study years (Table 3), but itis a peculiarity of small pelagic fish. Thehigher B values are in 1998: about 13.000 twith both method; the lower in 1999: 2404t with the new method and 3231 t with theold one (Table 3).The proportion of variation in biomassabundance, except 1998, is about 30%,(Figure 6). About 1998, the discrepancypercentage is not significant both for S andB: 0.16% (Figure 6). The greater differencebetween the first estimates and thesecond re-evaluation has been recorded in2005 with S variation of 55% and valueschanging from 0.218 to 0.339 (Table 3;Figure 4). Biomass variability was also relevant(35.6%) with values from 12729 to8200 (Table 3; Figure 5). In this year therearen’t POF 0 (Table 1): this confirms that ifthere aren’t samples immediately after the2119