Title: The Scientific Method for Solving Problems
1The Scientific Methodfor Solving Problems
- Martha Rosemeyer
- Eco Ag/Organic Seed
- April 1, 2004
2Outline
- 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
3Why 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
4I. 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?
5Example
- You are watching pea seedlings come up in certain
areas of field come up yellow
6Observe the plant closely
- Dark brown collar near soil line (crown) of plant
- Plant can fall over
- Photo is of soybean damping off
7Observe the pattern in the field
- You notice that low spots in the field have the
symptom - Low spots collect water remain damp
8II. 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.
9WSU Extension Bulletin
10WSU 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
11III. 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
12Hypothesis
- 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.
13IV. 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
15Three 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 .
163) 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
17Pea with Pythium root rot vs. control
18Pea damping off and root rot due to Pythium
19A 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?
21V. 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.
23Thats 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
24How 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
25A 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!
26The 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!
27Scientific 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
28References
- The Scientific Method cjcarter _at_ uc.edu.