MANAGEMENT AND ANALYSIS OF MANAGEMENT AND ANALYSIS OF WILDLIFE BIOLOGY DATA WILDLIFE BIOLOGY DATA Bret A. Collier Bret A. Collier 1 and T. Wayne and T. Wayne Schwertner Schwertner 2 1 Institute of Renewable Natural Institute of Renewable Natural Resources, Texas A&M University, Resources, Texas A&M University, College Station, TX 77845, USA College Station, TX 77845, USA 2 Department of Animal Sciences and Department of Animal Sciences and Wildlife Management, Tarleton State Wildlife Management, Tarleton State University, Stephenville, TX 76402 University, Stephenville, TX 76402
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MANAGEMENT AND ANALYSIS OF WILDLIFE BIOLOGY DATA Bret A. Collier 1 and T. Wayne Schwertner 2 1 Institute of Renewable Natural Resources, Texas A&M University,
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MANAGEMENT AND ANALYSIS MANAGEMENT AND ANALYSIS OF WILDLIFE BIOLOGY DATAOF WILDLIFE BIOLOGY DATA
Bret A. CollierBret A. Collier11 and T. Wayne and T. Wayne SchwertnerSchwertner22
11Institute of Renewable Natural Resources, Texas A&M Institute of Renewable Natural Resources, Texas A&M University, College Station, TX 77845, USAUniversity, College Station, TX 77845, USA
22Department of Animal Sciences and Wildlife Department of Animal Sciences and Wildlife Management, Tarleton State University, Stephenville, Management, Tarleton State University, Stephenville,
TX 76402TX 76402
IntroductionIntroduction
In wildlife biology, data analysis underlies nearly all the In wildlife biology, data analysis underlies nearly all the research that is conductedresearch that is conducted
The range of statistical methods available is extensiveThe range of statistical methods available is extensive
Ultimately, good questions, study designs, and analysis Ultimately, good questions, study designs, and analysis are complementary topicsare complementary topics
First ThoughtsFirst Thoughts
When designing a study: Talk to a professionalWhen designing a study: Talk to a professional
No amount of statistical exorcism can fix a bad study No amount of statistical exorcism can fix a bad study designdesign
Methods are rapidly advancing, staying in front is toughMethods are rapidly advancing, staying in front is tough
Again: When designing a study: Talk to a professionalAgain: When designing a study: Talk to a professional
Study DesignStudy Design In scientific research, results hinge on study designIn scientific research, results hinge on study design
Define population of interestDefine population of interest Ecological populationsEcological populations Inferential populationsInferential populations Target populationsTarget populations Sampled populationsSampled populations
Population inference requires data representing Population inference requires data representing population of interestpopulation of interest
Data CollectionData Collection Conceptual framework for ‘how’ to collectConceptual framework for ‘how’ to collect
1. Outline study question.1. Outline study question. 2. Define response variable (e.g., nest survival).2. Define response variable (e.g., nest survival). 3. Define explanatory and/or descriptive variables that might affect 3. Define explanatory and/or descriptive variables that might affect
response (e.g., vegetation cover).response (e.g., vegetation cover). 4. Define steps for minimizing missing data.4. Define steps for minimizing missing data. 5. Outline data collection approach.5. Outline data collection approach. 6. Design initial data collection instrument specific to response or 6. Design initial data collection instrument specific to response or
explanatory variables.explanatory variables. 7. Conduct field test of protocols and data instruments.7. Conduct field test of protocols and data instruments. 8. Evaluate efficiency of data instruments.8. Evaluate efficiency of data instruments. 9. Repeat steps 2–8 if necessary due to logistical difficulties.9. Repeat steps 2–8 if necessary due to logistical difficulties. 10. Initiate data collection.10. Initiate data collection.
Data ManagementData Management Data typesData types
QualitativeQualitative QuantitativeQuantitative
Data measurement scalesData measurement scales NominalNominal OrdinalOrdinal IntervalInterval RatioRatio
Data filesData files Files containing all data in rows and columnsFiles containing all data in rows and columns Commonly put into spreadsheetsCommonly put into spreadsheets More advantageous-database management systemMore advantageous-database management system
Data PresentationData Presentation Tables and GraphsTables and Graphs
Hypothesis DevelopmentHypothesis Development Good questions come from good hypotheses about how Good questions come from good hypotheses about how
a process occursa process occurs
Statistical models can help evaluate strength, or lack Statistical models can help evaluate strength, or lack thereof, of how a process occursthereof, of how a process occurs
Models should inform the ecological question, not drive Models should inform the ecological question, not drive the questionthe question
Hypothesis DevelopmentHypothesis Development Good questions come from good hypotheses about how Good questions come from good hypotheses about how
a process occursa process occurs
Statistical models can help evaluate strength, or lack Statistical models can help evaluate strength, or lack thereof, of how a process occursthereof, of how a process occurs
Models should inform the ecological question, not drive Models should inform the ecological question, not drive the questionthe question
F-tests (F-tests (Analysis of Variance)Analysis of Variance)
CorrelationCorrelation
Regression AnalysesRegression Analyses
Linear RegressionLinear Regression
Multiple RegressionMultiple Regression
Generalized Linear ModelsGeneralized Linear Models
Community AnalysisCommunity Analysis Wildlife research has traditionally focused on the Wildlife research has traditionally focused on the
population level.population level.
Some study questions, however, address how wildlife Some study questions, however, address how wildlife communities:communities: Respond to management activities or other perturbationsRespond to management activities or other perturbations Biodiversity is affected by various activities Biodiversity is affected by various activities Change across space and time Change across space and time
Species RichnessSpecies Richness Number of species in a community.Number of species in a community.
Strongly influenced by sample size.Strongly influenced by sample size. Makes comparisons difficult.Makes comparisons difficult.
Complete EnumerationComplete Enumeration Provides the minimum number of species present.Provides the minimum number of species present.
Works for simple communities.Works for simple communities.
Rarely possible.Rarely possible.
Richness IndicesRichness Indices Margalef’s indexMargalef’s index
►Not an estimate.Not an estimate.
►Cannot be compared with other indices or richness Cannot be compared with other indices or richness estimates.estimates.
►Strongly influenced by sample size.Strongly influenced by sample size.
Richness EstimatesRichness Estimates Estimate the actual number of species in the communityEstimate the actual number of species in the community Data collected as a single sampleData collected as a single sample
►RarefactionRarefaction Used for standardizing sample sizes, and the resulting estimates of species Used for standardizing sample sizes, and the resulting estimates of species
richness, among samples.richness, among samples.
►Chao 1 MethodChao 1 Method Especially useful when a sample is dominated by rare species.Especially useful when a sample is dominated by rare species. Requires species abundance data.Requires species abundance data.
Data collected as a series of samples.Data collected as a series of samples.►Chao 2 MethodChao 2 Method
Modified Chao 1Modified Chao 1 Can be used with presence-absence dataCan be used with presence-absence data
► Jackknife and Bootstrap estimatesJackknife and Bootstrap estimates
Involve systematically resampling the original datasetInvolve systematically resampling the original dataset ..
Species HeterogeneitySpecies Heterogeneity Measures the degree to which individuals in a Measures the degree to which individuals in a
community are distributed among the species present.community are distributed among the species present.
►Shannon-Weiner FunctionShannon-Weiner Function Based on information theoryBased on information theory Measures the amount of uncertainty associated with predicting the Measures the amount of uncertainty associated with predicting the
species of the next individual to be collected.species of the next individual to be collected.
►Simpson IndexSimpson Index The probability that 2 individuals drawn randomly from a community The probability that 2 individuals drawn randomly from a community