Scientific method

• Hypothesis


  Suggested explanation or a reasoned prediction of an observation made before the experiment
• Theory


  A tested, well-substantiated, well-known unifying explanation for a set of verified, proven factors
• Theory


  • Backed by evidence
• Hypothesis


  • Only suggested possible outcome
• Inductive reasoning


  Making observations, discerning a pattern, making a generalization, and inferring an explanation & eventually a theory
• Inductive reasoning


  • Elephants depend on water – all observed animals depend on water to exist – all biological life depend on water to exist
• Deductive reasoning


  Using existing theories to make conclusions about specific cases, e.g. prediction formation
• Deductive reasoning


  • All spiders have 8 legs – A tarantula is a spider – Therefore it must have 8 legs
• Deductive reasoning


  • The conclusions can only be true if all the premises set in the inductive study are true
• Constant interplay between inductive reasoning (based on observations) and deductive reasoning (based on theory), until we get closer and closer to the 'truth' (temporary truth – never certainty)
• Experiment - Methods


  Hypotheses are tested either in laboratory (artificial settings) or in field investigations (natural settings) through experimentation
• Experimental design


  • Involves the listing of all the materials & steps to be used
  • Controlled experiments – typically in the lab
  • Uncontrolled (observational) experiments – typical in the field
  • In such a way that it is repeatable by you & others
• Controlled experiments


  • Conditions can be manipulated
  • Control group – contains the variable (factor) that is being tested (dependent variable) but not the independent variable
• Variable


  • Specific aspects of objects or events that may differ or change over time and among individuals in your experiment
  • Dependent (response) variable – the variable of interest, the variable whose behaviour we are trying to explain
  • Independent (explanatory) variable – a variable that may influence or explain the behaviour of the variable of interest
• Variable


  • How does the time water is heated influence water temperature?
  • What would happen to a plant if it is given other forms of hydration other than water?
• Uncontrolled experiments


  • Wild (natural) settings
  • No interference (manipulation) of the system
• Uncontrolled experiments


  • Feeding behaviour of birds
  • Behavioural patterns in chimps
  • Attaching data loggers to animals
• Sampling


  • Process of selecting units from whole populations/ groups
  • Replication or repetition is necessary to verify that the results obtained are valid & consistent
  • Random sampling – to avoid bias in your results
  • Larger sample size – individuals vary in genetic make up, size, health & accidents
  • True representation of the whole
• Model


  • Physical, conceptual or mathematical representations of real natural phenomena
  • A model is any simplification, substitute or stand-in for what you are actually studying or trying to predict – predictions and what ifs
  • Models are used because they are convenient a substitute for the real thing – connect the dots
  • Used to explain and predict the behaviour of real objects/organisms/systems - Intuition
• Model organisms


  • Organisms used to study fundamental phenomena with the expectation that findings can be applied to other systems
  • Properties of a good model organism: Short lifespan, Quick maturation and reproduction, Produce large number of offspring, Easy to manipulate, Well understood physiology and behaviour, Sequenced and known genome
• Model organism


  • Drosophila melanogaster (common fruit fly)
• Results


  • Draw conclusions based on the data we received
  • Accept or reject the null hypothesis
• Data


  • Recorded observations or items of information
  • Measure, count & simply observe the results
  • Qualitative - descriptions
  • Quantitative - recorded measurements
• Results are presented in graphs and tables
• Discussion


  • The mere collection of data is useless unless the collected data is understood & used to make appropriate inferences & conclusions
  • Data should be analysed and interpreted, to be able to draw conclusions
  • Compare with past scientific studies
• Conclusion


  • Gives a summary of the results
  • Gives a summary of what they mean
  • Makes a decision about the hypothesis- whether the hypothesis is valid, invalid, can be accepted or rejected, needs to be refined or reformulated
• Scientific articles and Peer Review

  • Scientists report their results in scientific articles in scientific journals
  • Other scientists, other experts in the respective field, reviews the articles to fix small errors, flaws in their logic, flaws in experimental design, mistakes, fraud
  • Journal editors, who are also experts in their field then act as the go between to decide if an article should be published or not