number of baskets in the set. This has been done for numbers of 

 baskets between 20 and 80 as shown in table 6. 



In order to compute the 95-percent limits of the average of 

 several fishing stations it must be assumed that the stations share a 

 common variance. This assumption appears to be met within the 

 central Pacific area, but might not apply between the central Pacific 

 and other areas, where such factors as the schooling habits of the 

 fish might differ. Following this assumption, it is only necessary 

 to sum the number of baskets involved and calculated a new 2 a- 

 based on the relationship of the number of baskets involved to the 

 number used in calculating the basic (r (.458 for 20 baskets), 9/ 



Table 6. Two sigma (95-percent) limits for catches of 

 yellowfin tuna made on the gear used by 

 Pacific Oceanic Fisheries Investigations. 



9/ Actually, this procedure is valid only for geometric means, but 

 it is a useful approximation if the catches do not range through 

 orders of magnitude. If these conditions are not met, the method 

 developed by Sette and Ahlstrom (1948) for setting fiducial limits 

 on logarithnmically transformed data appears nnore appropriate. 



20 



