BIO318: Statistics Workshop A brief primer on the use of statistics in the study of animal behaviour

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BIO318 Statistics WorkshopA brief primer on the
use of statistics in the study of animal behaviour
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Outline

• What is Statistics?
• Why do we use Statistics?
• Some simple guidelines
• Overview of the assignment
• Useful resources
• Questions

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What is Statistics?

• A branch of applied mathematics concerned with
  the collection and interpretation of quantitative
  numerical data
• http//wordnet.princeton.edu/

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Optimal Foraging DataHandling Time (s)
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Simple Guidelines

• What is your question? Your hypothesis?
• Describe the structure of your data
• Graph your raw data
• Decide what statistical test to employ
• Is your data parametric or not?
• Find an appropriate resource to carry out
  statistical test
• Interpret the results of statistical test
• Write-up the results and display the summary
  statistics

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Simple Guidelines

• What is your question? Your hypothesis?
• Describe the structure of your data
• Graph your raw data
• Decide what statistical test to employ
• Is your data parametric or not?
• Find an appropriate resource to carry out
  statistical test
• Interpret the results of statistical test
• Write-up the results and display the summary
  statistics

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1. Cricket Aggression Experiment

• Question
• What is the effect of female presence on
  male-male aggression in the house cricket, Acheta
  domesticus?
• Hypothesis
• Female presence affects the aggressive behaviours
  of male crickets.
• Prediction
• During aggressive contests, pairs of males in the
  presence of a female will behave differently than
  pairs of males on their own.

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Simple Guidelines

• What is your question? Your hypothesis?
• Describe the structure of your data
• Graph your raw data
• Decide what statistical test to employ
• Is your data parametric or not?
• Find an appropriate resource to carry out
  statistical test
• Interpret the results of statistical test
• Write-up the results and display the summary
  statistics

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2. Cricket Aggression Raw DataAggressive Song
Duration (s)
Independent Variable? Dependent Variable? of
IVs? Type of IV? Type of DV?
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Simple Guidelines

• What is your question? Your hypothesis?
• Describe the structure of your data
• Graph your raw data
• Decide what statistical test to employ
• Is your data parametric or not?
• Find an appropriate resource to carry out
  statistical test
• Interpret the results of statistical test
• Write-up the results and display the summary
  statistics

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3. Graph your raw data
Song Duration (s)
Without Fem. With Fem. Treatment

• Check for data entry mistakes
• Helps you decide on the proper statistical test

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3. Graph your raw data
Song Duration (s)
Without Fem. With Fem. Treatment

• Check for data entry mistakes
• Helps you decide on the proper statistical test

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3. Graph your raw data
Song Duration (s)
Without Fem. With Fem. Treatment

• Check for data entry mistakes
• Confirms how you thought your data was organized

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3. Graph your raw data
Song Duration (s)
Without Fem. With Fem. Treatment
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3. Graph your raw data
Song Duration (s)
Without Fem. With Fem. Treatment
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3. Graph your raw data
Song Duration (s)
Without Fem. With Fem. Treatment
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3. Graph your raw data
Song Duration (s)
Without Fem. With Fem. Treatment
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3. Graph your raw data
Song Duration (s)
Without Fem. With Fem. Treatment
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Simple Guidelines

• What is your question? Your hypothesis?
• Describe the structure of your data
• Graph your raw data
• Decide what statistical test to employ
• Is your data parametric or not?
• Find an appropriate resource to carry out
  statistical test
• Interpret the results of statistical test
• Write-up the results and display the summary
  statistics

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4a. Choose Your Own Statistical Analysis
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Simple Guidelines

• What is your question? Your hypothesis?
• Describe the structure of your data
• Graph your raw data
• Decide what statistical test to employ
• Is your data parametric or not?
• Find an appropriate resource to carry out
  statistical test
• Interpret the results of statistical test
• Write-up the results and display the summary
  statistics

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4b. Assessing Parametric AssumptionsFrequency
Histograms
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4b. Assessing Parametric AssumptionsBoxplots
Song Duration (s)
Without Fem. With Fem. Treatment
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Simple Guidelines

• What is your question? Your hypothesis?
• Describe the structure of your data
• Graph your raw data
• Decide what statistical test to employ
• Is your data parametric or not?
• Find an appropriate resource to carry out
  statistical test
• Interpret the results of statistical test
• Write-up the results and display the summary
  statistics

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5. Pick Your Analysis Program

• On-line tools
• Statistics software

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Simple Guidelines

• What is your question? Your hypothesis?
• Describe the structure of your data
• Graph your raw data
• Decide what statistical test to employ
• Is your data parametric or not?
• Find an appropriate resource to carry out
  statistical test
• Decipher the output of statistical test
• Write-up the results and display the summary
  statistics

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6. Deciphering the Output

• Null Hypothesis (H0)
• No difference between two categories of IV
• Alternative Hypothesis (Ha)
• Categories of IV differ from one another

If p lt 0.05, then reject H0 (i.e. H0 is false,
therefore Ha must be true)
If p gt 0.05, then do not reject H0 (i.e. results
inconclusive)
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Simple Guidelines

• What is your question? Your hypothesis?
• Describe the structure of your data
• Graph your raw data
• Decide what statistical test to employ
• Is your data parametric or not?
• Find an appropriate resource to carry out
  statistical test
• Decipher the output of statistical test
• Write-up the results and display the summary
  statistics

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7. Summarize Data
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7. Summarize Data

• Results
• clear, concise, objective
• do not interpret data
• indicate the direction of effect, if any
• give test statistics, sample sizes, p-values

Figure 1 Give a descriptive caption.
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Statistics Assignment

• analyze the six different aggressive behaviours
• make sure to use the appropriate parametric or
  nonparametric test
• write a results section
• construct figures to display results

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