Key variables |
Budget to fixed cost ratio, B/c
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Scaled budget, B′ |
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Coefficient of variation, θ = σ/µ
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Scaled fixed cost, c′ |
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Target probability of failed detection, Qc
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Main results |
When the detection rate is highly variable it is optimal to have more, shorter surveys than when it is relatively constant. |
The solution is relatively insensitive to changes in the coefficient of variation, θ. |
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A tougher management objective (lower Qc) results in fewer, longer surveys. |
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For rare or cryptic species it is optimal to have fewer, longer surveys than for common species. |
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The analytic approximation derived for each objective function performed well. |
Minimum survey effort |
When detection rate varies, more effort is required to ensure management objectives are met. |
Treefrog surveys (B = 10 hours, Qc = 0.95) |
When the expected abundance is1, 3 surveys are optimal. |
When the expected abundance is1, 2 surveys are optimal. |
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When the expected abundance is3, 4 surveys are optimal. |
When the expected abundance is3, 4 surveys are optimal. |
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Correlation between time-steps only affected the solution when the correlation coefficient was quite large. |
Plant surveys Atriplex semibaccata µ = 0.55, σ = 0.60 Lomandra longifolia µ = 0.56, σ = 0.64 |
The predicted optimal number of quadrats ranged between 1 (for both species when budget B = 5 and fixed cost c = 1) and 11 quadrats (for L. longifolia when B = 15 and c = 0.25). |
The predicted optimal number of quadrats ranged between 1 quadrat (for both species when B = 5) and 16 quadrats (for both species when B = 15 and c = 0.25) |
(Qc = 0.95) |
The predicted number of quadrats was very close to the empirically-derived optima. |
The predicted and observed optimal numbers of quadrats did not correspond as closely but were still strongly correlated. |