1. BIOL 4240 Field Ecology

2. Data, data everywhere
“Modern science proceeds by conjecture and refutation, by hypothesis and test, by ideas and data, and it also proceeds by obtaining good descriptions of ecological events”.
Krebs 1999 p.1

3. Data, data everywhere What data should be collected?
What is useful and useless?

4. Data, data everywhere Krebs rules…
Not everything that CAN be measured SHOULD be measured
Find a problem and state your objectives clearly
Collect data that will achieve your objectives and make a statistician happy.
Some ecological questions are impossible to answer at the present time

5. http://www.lazyjames.co.uk /hotrock/malawi.html
Hierarchical review…
attractions/lake_malawi.asp?css=1
/hotrock/malawi.html
Biosphere
Region
Landscape
Ecosystem
Community
Population
Individual (organism)
gallery_app/view_photo.php ?set_albumName=malawi&id= DSC01998_lake_malawi_fish
/geocover/geocoverortho/ gcorthoregional/africa_mosaic.jpg/view

6. Many ecological questions involve populations…
¿What are the 3 populations that exist?

7. Controlled vs. uncontrolled events…
¿What is the difference between spatial and temporal scales/studies?

8. Intervention analysis…
% Nest success
Year

9. Other scales of measurement…
¿What is the difference between …
*Nominal
*Ranking
*Interval and ratio
scales?

10. Continuous OR Discrete…
¿What is the difference?

11. Continuous-ly worrying about precision and accuracy…
¿What is the difference?
¿How does implied precision vary?
SVL in mm for Idaho Giant Salamanders 73
73.4
73.47

12. Identify the following types of data
Month when hibernation begins
Mass of salamanders
Number of salamanders > 50mm svl
Temperature of stream water

13. ¿How many significant figures should you measure?
The rule of 300
Sokal and Rohlf’s method
Determine range of your data
Range/30 AND Range/300 OR
Barford’s method

14. More of Kreb’s rules
With continuous data, save time and money by deciding on the number of significant figures needed in the data BEFORE you start an experiment
When conducting calculations… your answer is only as good as your weakest link.
¿What is meant by this?

15. To Describe or to Infer that is the question…
¿What are the limits of inference?
At least 3 problems related to inference…
Statistical populations
Confounding/hidden variables
Bias
Δ Read a sample abstract and then determine the limit of inference…

16. More of Kreb’s rules
Never report an ecological estimate without some measure of its possible error

17. ¿ Black and white… or shades of gray?
The value of a p value…
¡Be sure you know the difference between statistical and biological significance!

18. More of Kreb’s rules
Be skeptical about the results of statistical tests of significance.
Never confuse statistical and biological significance
Evaluate the statement “Null hypotheses are irrelevant to ecologists”

19. More of Kreb’s rules
Make a data form and enter your data into a spreadsheet/database
Garbage in, garbage out
¿What can you do to minimize “garbage”?