Average number of samples needed to estimate 

 abundance and species per sampling unit at 

 precision levels of 50 and 30 percent at 

 a 95-percent confidence level during Imperial 

 Beach study. 



Depth 



50 



Abundance (pet ) 



30 



50 



Species (pet) 



30 







intertidal 



49 



85 



17 





44 



3. 7 meters 





14 



6 





10 



6.1 meters 



6 



11 



5 





8 



If P = precision and Y = confidence level, the true population mean will 

 lie within +P% of the measured mean Y% of the time. Sample number esti- 

 mates are derived from an actual data series and do not assume a normal 

 distribution of data points. 



Table 8. Frequencies of different distribution types for abundance 

 per sample and species per sample during Imperial Beach 

 studv. 





Contagious 

 (aggregated) 



(pet) 



Random 



(pet) 



Even 

 (pet) 



1 



INTERTIDAL 









Individuals per sample 



92.3 



7.7 







Species per sample 



30.8 



69.2 







3. 7- METER DEPTH 









Individuals per sample 



61.3 



38. S 







Species per sample 







84.6 



15.4 



6.1- METER DEPTH 



■ 







Individuals per sample 



72.7 



27.3 







Species per sample 



9.1 



63.6 



27.3 



49 



