To evaluate the adequacy of impingement data, El-Shamy calculated a 

 confidence limit (+ 2 SE) for the mean number of a species impinged per 

 day in each month and over a year. Precision was the X divided by 2SE. 

 To determine if improvements in the precision could be obtained given a 

 fixed annual level of effort, he used a stratification and optimum 

 allocation approach. This approach was applied to Millstone data as 

 follows. 



First, to verify those error estimates reported previously (NUSCo 

 1978) , precision of the annual mean daily estimates were calculated for 

 selected species grouped together. These included winter flounder, 

 cunner, blackfish, grubby, silversides, threespine stickleback, blue 

 crab, lady crab and American lobster. Calculations were limited to Unit 

 1, 1976 data since counts were made daily during that year. A comparison 

 of the precision associated with sampling schedules of 1 to 7 days/week 

 is given in Table 3. At a collection frequency of three days per week, 



a precision of 80% was achieved. Precision here is defined as 



2SE 

 1 ?r— . In theory, a complete census would yield a precision value of 



1.00 (Snedecor and Cochran 1978). Although the data bases and statistical 



techniques differ, a comparison of this analysis with NUSCo (1978) shows 



similar results; a 20-50% margin of error in the earlier study and an 



80% precision value in this study. As effort drops below 3 days/week 



the precision falls off rapidly. 



To determine if precision could be improved by redistributing and 



optimizing present effort, data collected at Units 1 and 2 from 1978-81 



were stratified by month and effort reallocated according to El-Shamy 



(1979). Annual and monthly precision factors were determined for the 



current program and for a reduced (10-50%) schedule of optimized sampling 



