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The Scientific Method for Solving Problems

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Title: The Scientific Method for Solving Problems


1
The Scientific Methodfor Solving Problems
  • Martha Rosemeyer
  • Eco Ag/Organic Seed
  • April 1, 2004

2
Outline
  • I. Observe your situation
  • II. Gather data from literature
  • III. Develop a testable hypothesis
  • IV. Test your hypothesis
  • V. Analyze data and determine whether
  • supports hypothesis or not

3
Why the scientific method?
  • Useful for solving certain types of problems
  • Methodological Françesco Redi and Louis Pasteur
    used the scientific method to disprove the
    widely-held idea of spontaneous generation
    (that life arises from nothing)
  • Technological In 1600s the invention of
    microscope permitted viewing of germ cells

4
I. Observation is key
  • Look at problem- invest in a hand lens for insect
    and disease problems
  • Pattern of plant problem on the plant
  • Pattern of plant w/problem in the field
  • What are the possible causes?
  • What can we test for?

5
Example
  • You are watching pea seedlings come up in certain
    areas of field come up yellow

6
Observe the plant closely
  • Dark brown collar near soil line (crown) of plant
  • Plant can fall over
  • Photo is of soybean damping off

7
Observe the pattern in the field
  • You notice that low spots in the field have the
    symptom
  • Low spots collect water remain damp

8
II. Check the literature
  • Extension bulletins
  • Peer-reviewed articles
  • Talk to other gardeners or farmers in your area
  • And to return to an example, Darwin not only
    observed and took notes during his voyage, but he
    also studied breeding and read the works of other
    naturalists to form his Theory of Evolution.

9
WSU Extension Bulletin
10
WSU bulletinCultural control of damping off
  • Do not overwater!
  • Do not plant in soils known to be infested with
    damping-off fungi.
  • Mulch to help raise soil temperature.
  • Plant in warm, well-drained soils during warm,
    dry weather (when possible).
  • Plant shallowly to encourage quick seedling
    emergence and growth.

--WSU publication
11
III. Formulate a hypothesis
  • Hypothesis is a statement that has two parts
  • Need a) testable explanation for the b)
    observation
  • Needs to be able to be tested by an experiment
  • Observation Yellowing and death at crown (where
    stem meets the soil) is due to damping off
    testable experiment

12
Hypothesis
  • The observed symptoms (lesions at soil line,
    yellowing) are due to damping off caused by a
    complex of fungi (Pythium sp., Rhizoctonia solani
    and Fusarium sp.).
  • What you observe is the effect and the hypothesis
    is the potential cause
  • Multiple hypotheses should be proposed wherever
    possible, e.g. The observed symptoms are due to
    Aphanomyces root rot or an insect.

13
IV. Test the hypothesis
  • Isolate the fungi from the diseased tissue
  • Reinoculate (apply fungi to) peas under sterile
    damp soil conditions
  • Observe symptoms-- are they the same?
  • Re-isolate the same fungus complex
  • This process ascribing causality of the pathogen
    with the symptoms is called Kochs postulates

14
  • Broth experiment to disprove spontaneous
    generation
  • broth in open flash (control treatment)
  • broth in closed, sterile flask (experimental
    treatment)
  • Data demonstrated that spoiled broth an microbes
    were present in open flask only in repeated tests
    (repetitions)
  • Therefore microbes did not arise by spontaneous
    generation
  • Conclusion(s) Organisms do not arise by
    spontaneous generation in this manner. To quote,
  • Life is a germ, and a germ is Life. Never will
    the doctrine of spontaneous generation recover
    from the mortal blow of this simple experiment.
  • --Louis Pasteur

15
Three essential ingredients of a scientific
experiment
  • 1) Treatment group
  • Pea plants are inoculated using agar with fungus
    complex
  • 2) Control group
  • ONLY difference between the two is only the ONE
    variable you wish to test
  • For example if you have the fungi on agar blocks
    and you are using the blocks for inoculation then
    your control is .

16
3) Repetitions
  • Why are repetitions needed?
  • Do all plants with symptoms have the pathogen
  • Does the fungus or pathogen complex cause the
    disease
  • Environment Does damping off arise only in damp
    spots
  • How many times do I need to repeat experiment?
  • Depends on variability in system

17
Pea with Pythium root rot vs. control
18
Pea damping off and root rot due to Pythium
19
A further hypothesis
  • You read in the literature and notice in previous
    plantings that a number of varieties of pea (in a
    variety trial) that smooth-seeded varieties have
    greater problems with damping off than wrinkled.
    You set out to test some new smooth and wrinkled
    pea varieties, as we will.

20
  • What is your hypothesis?
  • How would you test this?
  • Treatment, control, how many reps?

21
V. Determine if the results support the
hypothesis
  • Hypotheses can be proven wrong/incorrect, but can
    never be proven or confirmed with absolute
    certainty. They are supported by the
    experimental results
  • Impossible to test all given conditions, and
    someone in the future may find a condition under
    which the hypothesis does not hold true

22
  • Research is cumulative and progressive.
    Scientists build on the work of previous
    researchers, and one important part of any good
    research is to first do a literature review to
    find out what previous research has already been
    done in the field. Science is a process new
    things are being discovered and old, long-held
    theories are modified or replaced with better
    ones as more data/knowledge is accumulated.

23
Thats nice but how can I make my results
predictive?
  • Another way to say this is generalizable
  • This is where the compost tea experiment last
    quarter suffered-- not predictive
  • the worm bin compost (valid unto itself) and
    other compost were only one example, but this was
    a preliminary experiment

24
How to make the predictive case
  • More tests ie more round vs. wrinkled seeds
    inoculated and under damp conditions
  • Hypothesis-- Smooth peas on the market have a
    greater tolerance to damping off.
  • Has a predictive or generalizable result
    ultimately

25
A theory...
  • ..is a generalization based on many observations
    and experiments a well-tested, verified
    hypothesis that fits existing data and explains
    how processes or events are thought to occur.
  • Predictive
  • May be modified with new information
  • Theory in colloquial language means something
    not solidified, but it is much more tested than
    hypotheses!

26
The role of serendipity or a positive, unexpected
result
  • Sometimes serendipity (Serendib former name for
    Ceylon) happens
  • Chance favors the prepared
  • Important to be an observer, especially where
    your data doesnt fit your hypothesis!

27
Scientific method for round vs. wrinkled peas and
damping off
  • I. Observe your situation
  • II. Gather data from literature
  • III. Develop a testable hypothesis
  • IV. Test your hypothesis treatments, control,
  • repetitions
  • V. Analyze data and determine whether
  • results support hypothesis or not

28
References
  • The Scientific Method cjcarter _at_ uc.edu.
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