The Scientific Method for Solving Problems

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The Scientific Methodfor Solving Problems

• Martha Rosemeyer
• Eco Ag/Organic Seed
• April 1, 2004

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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

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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

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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?

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Example

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

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Observe the plant closely

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

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Observe the pattern in the field

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

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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.

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WSU Extension Bulletin
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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
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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

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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.

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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

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• 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

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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 .

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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

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Pea with Pythium root rot vs. control
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Pea damping off and root rot due to Pythium
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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.

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

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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

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• 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.

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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

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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

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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!

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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!

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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

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References

• The Scientific Method cjcarter _at_ uc.edu.