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3329992 
Journal Article 
Using variance components to estimate power in a hierarchically nested sampling design 
Dzul, MC; Dixon, PM; Quist, MC; Dinsmore, SJ; Bower, MR; Wilson, KP; Gaines, DB 
2013 
Yes 
Environmental Monitoring and Assessment
ISSN: 0167-6369
EISSN: 1573-2959 
185 
1 
405-414 
WOS:000312835300034 
We used variance components to assess allocation of sampling effort in a hierarchically nested sampling design for ongoing monitoring of early life history stages of the federally endangered Devils Hole pupfish (DHP) (Cyprinodon diabolis). Sampling design for larval DHP included surveys (5 days each spring 2007-2009), events, and plots. Each survey was comprised of three counting events, where DHP larvae on nine plots were counted plot by plot. Statistical analysis of larval abundance included three components: (1) evaluation of power from various sample size combinations, (2) comparison of power in fixed and random plot designs, and (3) assessment of yearly differences in the power of the survey. Results indicated that increasing the sample size at the lowest level of sampling represented the most realistic option to increase the survey's power, fixed plot designs had greater power than random plot designs, and the power of the larval survey varied by year. This study provides an example of how monitoring efforts may benefit from coupling variance components estimation with power analysis to assess sampling design. 
Devils hole; Power analysis; Nested sampling design; Variance components; Pupfish