the Scientific Method   and  the Scientist

       "Equipped with his five senses,
            man explores the Universe around him
                and calls the adventure Science."

                                      Edwin P. Hubble
                                    
  astronomer - 1948   A
 

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      Gk:   Bios = life     Logy = study of                                    
                              
the term biology was coined by Gottfried R. Treviranus in 1802.
          ______________________________________________________________________

     Physics is the study of atomic particles that interact by
                  a relatively simple set of rules that may be distilled
                  into predictive formulas.

    
     Chemistry is a more complicated application of physics & its rules,
   
     Biology, then could be a more complicated application of chemistry,
                  which also might be reducible to predictive physical formulas.
    
           but as we shall learn, Biology's rules are messy and its molecular
           interactions are almost impossible to faithfully predict.

the end of scientific method lecture outline

  
  






         Scientific Theories have 2 components:
            1.  one component describes  PATTERNs  observed in the natural world
           
2.  other component identifies a  PROCESS or MECHANISM  responsible for the pattern

  

      
SCIENTIFIC METHOD*
read this     ......is a manner for investigating Nature
           it's the methods by which scientists, collectively and over time, attempt to construct
           an accurate, reliable, consistent, and non-biased representation of the natural world

                    
    a way of investigating the things (patterns) we observe around us,
                        a way of recording... 
the laws (mechanisms) that govern our physical world
                  
     a systematic study of patterns of living things & their processes...
 
                                       it employs rigorous methodology and
                                         it devises experiments to validate observations...

       1. Observations .... and description of a phenomenon or group of phenomena.
 
                     from previous studies or directly... 
   
                   i.e., a gathering of the data... 
 
                    observed:
Bil 150students sitting in the back of the lecture hall, often fall asleep.
                           
                  
Begin to ask a Question: about the how's & why's of things you observe.
                          
in scientific method: questions must be framed in measurable terms

                   Look for Answers to Your Question:
                          
others may have asked & answered the same type of question.
                           do literature searches: textbook, journal & internet articles...
                               reading other people's findings may lead to more interesting questions;
                               and help define  or  modify your question better. 
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  2.
  Postulating a Premise.... 
formulating an explanation (hypothesis) of the phenomena
 
            the posing of a critical and experimentally testable question - 
                    Does sitting in back of Bil 150 classroom promotes sleep? 

         Develop possible explanations:


    
    Formulating a Hypothesis*....  to predict the existence of other phenomena,
                                                   or to predict quantitatively the results of new observations
             a tentative or possible explanation,
             a proposed explanation for a phenomena that is experimentally testable...
                            sitting in the back of the classroom keeps a student
                            out of reach of instructor, & its warm & cozy.
         
             one must state hypothesis as precisely as possible
             and must list the expected predictions that the hypothesis makes
...
                            
...often involves critical analysis  &  critical thinking
                             ...may also suggest an alternative hypotheses  -
  next                                                            "a boring lecture promotes sleep". 
 

 

 

 

 

 
4.
 Experimental Predictions...
   making a prediction that can be tested
          states results that may be expected
          from observations and/or from experimental tests
             moving a student from back to the front of the room can prevent sleep.
                     
               Design an Experiment to test your Hypothesis:
                       requires experience, creativity, and sense of what is practical.
                          read methods published by others - modify them to your purpose,
                          brainstorm with others - different perspectives are helpful,
                          you may be limited by equipment availability, costs, and time.
 
          experiments are supposed to test a premise... 
                           
moving one of two students to front will keep that student AWAKE ???
    

          experiments are best designed to DISPROVE, not to prove a hypothesis.
                                  
It is often said in science that theories can never be proved, only disproved.
                                   There is always the possibility that a new observation or a new experiment
                                                                  will conflict with a long-standing theory.

       
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     a Hypothesis can be refuted (proven wrong) or falsified
                      but a
hypothesis can never be proven right,
                      and evidence can be collected to provide support for a hypothesis...
   
               
thus, there is often no proof in science, only 'disproof':
    
       
                            an example...      Luis Alvarez (geophysicist) investigated assassination of JFK.
   

                            Premise:             backwards motion of JFK's head as fatal bullet struck proves at
                                                       least one shot must have come from front (dual shooter idea),
                                                       since a shot from behind would only push head forward.

  

                            Hypothesis:       "reflex of head requires a shot to have been fired from the front".

  

                            Experimental     Alvarez showed shot could have come from behind

                            disproof:           
             (laws of physics established a head can recoil backwards).
    

                            Conclusion:        experiment does Not Prove shot was from behind,
                                                       but does Disprove presumption that a shot must have come from front.

             when scientists publish they never say "results prove..."
                      
but rather "results suggest..."    or    "results provide support for..."

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 hallmark of the scientific method is...        DESIGNING an Experiment
     

      Purpose of an EXPERIMENT...
       
to disprove a hypothesis   or   to evaluate an alternative hypothesis  
             experiments should meet certain criteria
:
                unbiased...
                define the variables (see auxin experiment below)...
                 
  dependent variables: such as - number of parts, stem length, etc...
                        measurable & observable things; 
the variable modified by treatment
                   
independent variable: only one variable to be manipulated, which may change
                        time, height, weight, age, sex, amount of hormone, etc..., the treatment
                   
controlled variables:  those kept constant and not allowed to change
  
                     all experiments must have a control...  standard for comparison (a challenge)

                 example:  relationship of plant growth hormone auxin to plant growth:
                                     dependent variable: stem length (growth).
                                     independent variable: auxin amount
        
 next                 and controlled variables: temp, humidity, day length, amount of fertilizer.
 
                                                                                                                

 

 

 

 

          
             a big part of experimental design is
materials & methods (the procedures)
             based on previous published works, collegial suggestions, intuition, etc...   
  

             if auxin added to dwarf plants will stems to grow to normal height?  

    

               our experiments ought to include:

               1. controlnegative control: dwarf plants NOT given auxin
                                 positive control: normal plants NOT given auxin    
*
     

               2. proper concentration levels:
                                 should not be too low (no effect detected) nor too high (toxic);
                                 should be within physiological parameters of living cells

  

               3. 
must be recordable quantitatively measure length (mm)
  

               
4.  must be replicable...  redo several times, to be statistically valid
                                 
experiments ought to show consistent results
                                  again and again, from test to test
        
  

          
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     Protocols   &   Terminology of the Scientific Methodology...                
           one often makes predictions about outcome of an experiment:  that involves using...

    Hypothetico-Deductive Thinking...  which includes the formulation of an HYPOTHESIS,
                             (which is a tentative answer to a question) and doing experiments from which
                              may deduce a general answer to the hypothesis...   often involves

      
critical thinking... 
                 nothing is accepted as fact,  unless it is experimentally demonstrable
   

      
deductive reasoning... if...then logic
                  if all birds have feathered wings,
                         and a robin is a bird,
                               
then robins have feathered wings. 
  

       
  predictions for our auxin experiment:
               negative control: dwarf plants treated with water = remain short (dwarf)
               positive control: normal plants treated with water = normal height
               test treatment: dwarf plants treated with auxin = grow taller (normal)
       
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       Hypothetico-deductive methodology of scientific method also includes:
            
 
           inductive reasoning...
           
     is the ability to deduce intuitive/creative principles...
                       
                objects fall to ground when dropped
                       
                thus, a force must act on the object...       [gravity]
  

           is cumulative...
            - 
results from earlier studies become initial observations of new studies
            - everything that science "knows"  - even long established theories -
                    are subject to reexamination as new information is collected.

    
       - no endeavor of humankind rivals Science in its incremental progress
                      toward a more complete understanding of the observable world

   

           shows
adaptability... 
            -
not all experiments are clear cut, scientific results must fit into known facts:
         
           " all scientific knowledge is tentative, and open to challenge"    cm
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        Collection & Interpretation data...
   

 
         often draws upon previously known knowledge...
        scientists fit new knowledge into framework of what they already know...

  

 
               observations and measurements must always use same criteria...
                     
plant height always measured from pot rim to shoot tip
  

                variability
must be estimated...
                     
statistical analysis:     some common statistical tests include...
                          
t-test       - compares the means of two groups
                           ANOVA     - compares means of three (3) or more groups
                           chi square - compares how closely the observed or measured data
                                                    is to the expected results  (ex: genetic crosses)

 

   
         
   "Although concepts and ideas occupy a central place in the grand sweep of our under-
                    standing of the nature of the world around us, it is a mistake to imagine that they play a
                    greater role than
tools and techniques in achieving scientific progress.
                    Few scientific revolutions are concept driven
."   
          
[re: HGP].... John M. Thomas, 1994.
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              Organizing Data...   raw data is often expressed in tables and figures
 

                  tables:  often used to emphasize numbers themselves, rather than a trend

                  figures:  are graphs (trends),   pictures,   photos,   diagrams (visuals)
                                    line graphs - show effect of independent variable (X-axis) on
                                                          the dependent (measured) variable (Y-axis)
                                    bar graphs - compare sets of data that may be discontinuous
                                                          i.e., maybe different groups

                  the best way to display your data often depends on what you want to show
                             Examples*:   
aim is to show maximum growth rate is reached after several weeks

                    some fun experiments -  The Twinkie Project...    [Rice University finals Week 1995]
              
 next                                                                                1.3 - An introduction to  Graphing*.

 

 

 

 

 

 

               It's easy to formulate an initial hypothesis...
             It's hard to make a connection between cause and effect.
 
   

                Draw a conclusion...     if experimental outcomes match your predictions,
                                                   then your hypothesis is supported,
                                                                    if not, then your hypothesis is negated.
                     Do your results agree with findings of other?
                                
if not, do you know why not [different methods or species?]


  

                Experimental Results are a tool:  provide a sense of direction to experiments
                                do NOT let predictions affect your objectivity
                                do NOT make results fit your predictions (bias)                     
   

                     you may modify your hypothesis to fit the observed results...
                                    modifications of a hypothesis help scientists gain assurance
                                    that their explanations may be valid.
                     Negative results are often more important than positive ones:

          

  

                  
 next                            Campbell - Concept Activity - Investigations - Chapter 1
                                                         1.4 - How Do Environmental Changes Affect a Population
*
                                                         1.5 - How Does Acid Precipitation affect Trees*

 

 
 
 
 
 
 
 
 
   
    maybe you can formulate or substantiate a Theory...
                          ...the set of rules & procedures governing what we have observed
 

     
 a theory is... a hypothesis that has stood the experimental test of time
     
if experiments always bear out a hypothesis it might be regarded as a theory or law of nature

           In many scientific disciplines, the words "hypothesis",  "theory", and "law" can have different
           connotations in relation to  the stage of acceptance or knowledge about a group of phenomena.

          A hypothesis is a limited statement regarding cause and effect in specific situations;
          it also refers to our state of knowledge before experimental work has been performed
               Example: you discover that your car will not start. You may hypothesize...
               "My flashlight doesn't work, because the battery is dead."  your first hypothesis to test*.

          A scientific theory or law represents a hypothesis, or a group of related hypotheses,
          which has been confirmed through repeated experimental tests over a long period of time. 

                     "The philosopher ('scientist') proposes a solution in the form of a 'hypothesis',
                       as a revelation of '
truth' that has been tested experimentally, again and again".
                                                            
P. Haezrahi, 1970         paraphrased by chm 2002

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  the scientific method has limitations...
  
 

 

    How  many  of  you  believe  there  is  intelligent life  elsewhere  in  the  Universe ?*
 

 

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     fiber helix.gif (5957 bytes) 
   IRONIC SCIENCE... (non-testable theories, but which are scientifically based)

          Is there life elsewhere in the Universe ?
    

                
Greenhouse effect - its causes ? ...fossil fuel, deforestation?
                             

                Nuclear winter or meteor
(...a cause dinosaurs mass extinctions?  ice ages?) 
                               Mount St. Helens,      Gulf War
...      Earth-on-fire?       
  

                
Complexity & chaos theory?  makes it difficult to predict exactly
                      what is going to happen at any given time,  in the present or the future.
                     
   chaos theory deals with the behavior of nonlinear dynamical systems that are characterized
                               by sensitivity to initial conditions. Examples include the atmosphere, the solar system,
                               plate tectonics, turbulent fluids, economies, and population growth.

      

    
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ERROR in scientific experiments happens...    & can have have several sources.
     

          1.  There is error intrinsic to the instruments used for measurements --> random error.
  
          2.  There is non-random or systematic error, due to factors which may bias the results.
               No measurement, and therefore no experiment, can be perfectly precise...
  
                    A.  Human error:
                           
failure to follow procedures, failure to use the equipment properly,
                            failure to prepare solution correctly, measurements made by 2 researchers,
                            simple arithmetic errors, etc... 
  
                    B.
  Another common mistake is to rule out or ignore data which do not support
                            the hypothesis...  Humans have psychological tendency to find "something wrong",
                            with data, which does not support their hypotheses
        
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           ERROR cont.
                    C.  a scientist's personal bias can effect the outcome of an experiment...
                            most fundamental error is to mistake the hypothesis for an explanation of a
                            phenomenon
, without performing experimental tests. Sometimes "common sense"
                            and "logic" can tempt us into believing that no test is needed.
      

                                              
...teacher can hit student in front to keep awake  [bias]
       

                         Bias can be overcome... via open communication among members of the scientific
                         community  because experimental tests are repeated by different scientists...
                         using different types of experimental setups.

                    Sharing your results...    the PUBLISH or PERISH Rule
                         1.  in a paper in a referred (peer-reviewed) journal publication + Open Access
                         2.  at a poster session at a scientific meeting
                         3.  via seminars at scientific meetings or symposia

                              Over a period spanning a variety of experimental tests (usually several years),
                              a consensus develops in scientific community as to which experimental results

       
    next            have stood the test of time and become     ---->     THEORY.
    
      

 

 

 

 

 

 
         
     the word   THEORY... 
   
         to scientist the word THEORY means established FACT or TRUTH
 
            to lay person (philosopher) the word THEORY may mean...
                       
a speculation, a guess, an unknown,
or a lack of knowledge
  
    
the end of scientific method lecture outline
       
             Scientific Insanity:      doing the same experiment over & over,
                                                  but expecting a different result each time

             If Science is what scientists do the What Makes a Scientist*...
              the Earth
  paradigm - an archetypal model *     back

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         Last Update - 09/02/2008