3 April 2020

Goals for today

  • Identify features of data that drive analyses
  • Think critically about what the data could tell you

General approach

Question \(\rightarrow\) Data \(\rightarrow\) Model \(\rightarrow\) Inference \(\rightarrow\) Prediction

General approach

Question \(\rightarrow\) Data \(\rightarrow\) Model \(\rightarrow\) Inference \(\rightarrow\) Prediction

Common questions in ecology

At the individual level

Sex?

Fecundity?

Growth?

Survival?

Movement?

Common questions in ecology

At the population level

Abundance?

Survival?

Spatial distribution?

Movement/migration?

General approach

Question \(\rightarrow\) Data \(\rightarrow\) Model \(\rightarrow\) Inference \(\rightarrow\) Prediction

Ecological data

At the individual level

1 Detection \(\rightarrow\) presence/absence

2+ Detections \(\rightarrow\) survival, movement

Ecological data

At the individual level

1 Detection \(\rightarrow\) presence/absence

2+ Detections \(\rightarrow\) survival, movement


1 Measurement \(\rightarrow\) fecundity, age, size

2+ Measurements \(\rightarrow\) growth

Ecological data

At the population level

Detections \(\rightarrow\) presence/absence


Counts \(\rightarrow\) density or survival/movement

Data collection methods

Nonexhaustive counts

 

Data collection methods

Exhaustive counts

 

Data collection methods

(Non)exhaustive surveys

Depletions

 

Data collection methods

(Non)exhaustive surveys

Depletions

Capture/Tag/Recapture

 

Data types

Discrete values

Sex

Age

Fecundity

Counts/Census

Survival (individual)

Data types

Continuous

Size (length, mass)

Density

Survival (population)

A note on continuous variables

Approximating rational numbers with real numbers

Survival (7 of 9 survived \(\approx\) 0.78)


Composition (4 age-3, 18 age-4, 11 age-5 \(\rightarrow\) ~55% age-4)


Density (3 animals in 21 ha plot \(\approx\) 0.14 per ha)

A note on continuous variables

Approximating rational numbers with real numbers

Which of these give you more confidence?

A) 3 / 9 \(\approx\) 0.33

B) 300 / 900 \(\approx\) 0.33

The importance of raw data cannot be overstated

Distributions of data

Discrete distributions

Discrete distributions

Discrete distributions

Continuous distributions

Density \(\left(\mathbb{R}^{\geq}\right)\) \(\rightarrow\) log-Normal or Gamma

Continuous distributions

Density \(\left(\mathbb{R}^{\geq}\right)\) \(\rightarrow\) log-Normal or Gamma


Proportion \(\left(\mathcal{C}^D\right)\) \(\rightarrow\) Beta (D = 2) or Dirichlet (D > 2)

Continuous distributions

Density \(\left(\mathbb{R}^{\geq}\right)\) \(\rightarrow\) log-Normal or Gamma


Proportion \(\left(\mathcal{C}^D\right)\) \(\rightarrow\) Beta (D = 2) or Dirichlet (D > 2)


Transformations \(\left(\mathbb{R}\right)\) \(\rightarrow\) Normal