However, California did not conduct any matrix spikes with tissues. 
In terms of accuracy, California met the DQOs that the average deviation for all 
PCBs was within ±30% of the average value within the standard material as well as that 
70% of the individual PCB congeners were measured within ±35% of true value. Both 
Washington and Oregon failed the DQO that the average deviation for the PCBs should 
be within ±30% of the average value in the standard. Additionally, only 3 of the 17 PCB 
congeners measured in Oregon and none of the 10 congeners measured in Washington 
were within ±35% of the value in the standard. Because of this low accuracy when 
assessed with standard reference materials, the tissue PCB data from Oregon and 
Washington need to be interpreted cautiously. 
In both California and Oregon, the average percent deviation of the four DDTs 
measured in the reference material was less than or equal to the DQO of 30%. 
However, the value for 4,4'-DDE in Oregon differed from the reference material by 
>50%. In comparison, all four of the DDTs measured in Washington deviated from the 
standard reference material by >_63%. Because of the low accuracy when assessed 
with standard reference materials, the tissue DDT data from Washington and the 
Oregon 4,4'-DDE values should be interpreted cautiously. 
California analyzed only two of the 14 non-DDT pesticides in the standard 
reference material and did not conduct matrix spikes with tissues as an alternate 
demonstration of recovery. Accuracy for the compounds measured in the reference 
material (dieldrin and trans-nonachlor) was good; however without values for the other 
pesticides it is not possible to assess the overall accuracy for the non-DDT pesticides in 
California. Washington and Oregon measured most of the non-DDT pesticides in either 
their reference material and/or in a spiked matrix. Average deviation for the pesticides 
in both states failed the DQO and deviations for most individual pesticides were > 35% 
from the reference material or the spiked matrix. Because of the uncertain accuracy in 
the California tissue values and the low accuracy in Oregon and Washington, the tissue 
values for the non-DDT pesticides should be used cautiously. 
2.6 Statistical Data Analyses 
The use of a probability-based sampling design allows the development of 
estimates of the extent of area, with 95% confidence intervals, of the West Coast Shelf 
resource (30 - 120 m) corresponding to any specified value of the measured indicator. 
Analysis of indicator data was conducted by calculation of cumulative distribution 
functions (CDFs), an analysis approach that has been used extensively in other 
EMAP/NCA coastal studies (Summers et al. 1993, Strobel et al. 1995, Hyland et al. 
1996, U.S. EPA 2004, 2006). A detailed discussion of methods for calculation of the 
CDFs used in EMAP analyses is provided in Diaz-Ramos et al. (1996). Results of the 
CDF analysis are presented in the present report primarily as the values of an indicator 
which correspond to given percentiles of the cumulative distribution. Where known 
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