Scientific Methods, Terminology, and Reasoning

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Scientific Methods, Terminology, and Reasoning
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• Scientific methods are
• The most reliable means to ensure that
  experiments produce reliable information in
  response to a specific question.
• The steps taken to answer a specific question.

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STEPS

• Observations
• Form questions
• Make hypotheses
• Design an experiment
• Analyze results
• Make conclusions

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OBSERVATION

• In contemplating phenomenon that occur in nature,
  questions arise.
• Humans have the need to answer these questions
  thus experimentation occurs.

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Questions

• What questions do you have about your
  observations of the natural world?
• Why is the sky blue?
• What causes disease?
• What is a cure for cancer?
• Why can you only have a particular virus
  once?

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Hypotheses

• After carefully researching topics that relate to
  the question- hypotheses can be formulated.
• A hypothesis is
• A logical but unproven explanation for a given
  set of facts.
• Developed through observations or previous
  experiments
• Usually an If/then statement
• Ex. If the plant is not watered, then it will die.

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Experiments

• Tests a hypothesis by collecting information
  under controlled conditions.
• There are two groups in an experiment
• Control group all conditions kept normal
• Experimental group (test group) all conditions
  kept the same as the control except for the
  single condition being tested.

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Variables

• Independent variable experimental variable- the
  thing changed (tested) in the experiment.
• Dependent Variable changes in this condition
  depends on changes in the independent variable.
• The dependent variable depends on the independent
  variable.

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• Ex. You want to test the effect of light on the
  growth of tomato plants.

What is the independent variable? What is the
dependent variable? Your control group would be
put in what conditions?
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Data

• Quantitative numerical counts or measurements
• Scientific measurements are always metric
• Reported in graphs or tables
• Qualitative (descriptive) written descriptions.

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• Data lends support for or against the hypothesis
• When a hypothesis is supported over time by many
  investigations is becomes a theory
• Ex. Theory of Inheritance
• Facts of nature generally known to be true are
  laws
• Ex. Law of Gravity

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Designing Experiments

• The PurposeThe purpose clearly states the
  phenomenon or question you plan to investigate.
• Your purpose should guide your experimentation
  and help keep you on track.

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Hypotheses

• The next step is to formulate hypotheses.
• An hypothesis is your informed prediction about
  the outcome of your research.

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Variables

• You should clearly state the variables in your
  experiment.
• These include dependent, independent as well as
  controlled variables.

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Procedure

• Raw data by itself is meaningless unless people
  know how it was collected.
• You should describe the method you followed to
  obtain your data as well as the materials and
  equipment used so that anyone could reproduce
  your experiment at a later date.

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Results

• This includes all the data you collect from your
  procedure. All data, whether it fits with what
  you expected or not, must be recorded.
• Your results should be presented in the clearest
  way possible. Quite often this will include
  graphs and charts to show trends and
  relationships.

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Conclusions

• The conclusion must be based on the results of
  your experiment and should explain how you
  reached that conclusion.
• It should also include whether or not your data
  agrees with your hypothesis

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Communicate

• The last step is to communicate the results with
  others.
• Scientists publish their research in journals
  The New England Journal of Medicine.

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Reasoning

• In logic, we often refer to the two broad methods
  of reasoning as the deductive and inductive
  approaches.

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• Arguments based on experience or observation are
  best expressed inductively
• Arguments based on laws, rules, or other widely
  accepted principles are best expressed
  deductively.

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Deductive Reasoning

• Deductive reasoning works from the more general
  to the more specific. Sometimes this is
  informally called a "top-down" approach.

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• We might begin with thinking up a theory about
  our topic of interest. We then narrow that down
  into more specific hypotheses that we can test.
  We narrow down even further when we collect
  observations to address the hypotheses. This
  ultimately leads us to be able to test the
  hypotheses with specific data -- a confirmation
  (or not) of our original theories.

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• "Deductive reasoning" refers to the process of
  concluding that something must be true because it
  is a special case of a general principle that is
  known to be true.
• For example, if you know the general principle
  that the sum of the angles in any triangle is
  always 180 degrees, and you have a particular
  triangle in mind, you can then conclude that the
  sum of the angles in your triangle is 180
  degrees.
• Deductive reasoning is logically valid.

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Inductive Reasoning

• Inductive reasoning works the other way, moving
  from specific observations to broader
  generalizations and theories. Informally, we
  sometimes call this a "bottom up" approach
  (please note that it's "bottom up" and not
  "bottoms up" which is the kind of thing the
  bartender says to customers when he's trying to
  close for the night!).

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• In inductive reasoning, we begin with specific
  observations and measures, begin to detect
  patterns and regularities, formulate some
  tentative hypotheses that we can explore, and
  finally end up developing some general
  conclusions or theories.

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• Inductive Reasoning is the process of reasoning
  that a general principle is true because the
  special cases you've seen are true.
• For example, if all the people you've ever met
  from a particular town have been very strange,
  you might then say "all the residents of this
  town are strange". That is inductive reasoning
  constructing a general principle from special
  cases.
• Inductive reasoning is not logically valid. Just
  because all the people you happen to have met
  from a town were strange is no guarantee that all
  the people there are strange.

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• These two methods of reasoning have a very
  different "feel" to them when you're conducting
  research. Inductive reasoning, by its very
  nature, is more open-ended and exploratory,
  especially at the beginning. Deductive reasoning
  is more narrow in nature and is concerned with
  testing or confirming hypotheses.