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Power analysis for a Mark recapture project

Power analysis for a Mark recapture project. Dan Bachen Department of Ecology Montana State University. Project overview. Data collection Blacktail WMA 24 plots 4 weeks . Mark Recapture. Data collection Methods Trap grids 8x8 Sherman live traps 5 nights per plot Unique marks

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Power analysis for a Mark recapture project

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  1. Power analysis for a Mark recapture project Dan Bachen Department of Ecology Montana State University

  2. Project overview • Data collection • Blacktail WMA • 24 plots • 4 weeks

  3. Mark Recapture • Data collection Methods • Trap grids 8x8 • Sherman live traps • 5 nights per plot • Unique marks • 4 species • Deer mouse dominant > 90% of captures

  4. Data example

  5. Power analysis • Goals • Optimize sample size • Treatment effect -.1 to -1 • 20 sites used (10 treatment, 10 control) • 40 sites used (20 treatment, 20 control) • Effect of -.84 recorded by Ostoja 2009 • Assumptions • Abundance estimates normal • Capture probability • .2 un-captured individuals • .9 captured individuals

  6. Power analysis • Methods • Generate abundances using likelihood analysis (Rcapture) • Quantify statistics • Use statistics to set parameters • Iterate experiment • Score success

  7. Results Mean: 7.44 SE: 5.84

  8. Results

  9. Results

  10. Discussion • Experiment might have worked • Did I use the right tools? • No • Aggregation of samples • Example: • Abundance= 158.2 • SE= 2.3

  11. Future Work • Re-run power analysis aggregating samples • New tools • RMark • Compare results to other techniques

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