The Scientific Method

1
The Scientific Method

• Lecture 1
• Introduction to the Scientific Method

2
The Scientific Method

• In this lesson, we will
• Explore what is meant by scientific method
• Discuss the concept of a testable hypothesis
• Consider examples of possible investigative
  projects

• By the end of this exercise, you should be able
  to
• State the principles of scientific investigation
• Explain, using suitable examples, the terms
  hypothesis, null hypothesis, prediction, data and
  variation in relation to scientific investigation
• Propose a topic for a practical scientific
  investigation, considering resource, time and
  ethical constraints

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The Scientific Method

• Scientific research seeks to correctly describe
  and explain what can be observed
• directly by human senses
• by technological extension(eg using chemical
  tests, scientific instruments etc)
• A systematic approach that helps the planning,
  conduct, description and explanation of
  observations in a way people can understand
• Scientific Method is a conventional way of
  undertaking this activity and provides
• A means of convincing others that observations
  and explanations arereal and true
• A toolbox of useful methods and techniques that
  can be applied to a varietyof situations
• A fair and open process of review and revision of
  knowledge and understanding

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The Four Steps

• Observation
• Hypothesis
• Prediction
• Experiment (or evidence gathering)

Observations may prompt or be the deliberate
subject of investigation. They may be of an
event, a response, presence or absence, an
association or distribution etc that must be
described
Descriptions may be Qualitative e.g. a type of
behaviour, the shape of something, gender,
colour, presence/absence of a character Or Quantit
ative involving measurement or counting e.g.
height, weight, amount, number
Numbers are meaningless in themselves and must be
related to some other quality, the UNITS of
measurement
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Measurement
By international agreement, scientific
investigations use the SI (Systeme
Internationale) or MKS units of measurement
Derived Units describe many other properties of
observations in terms of the basic units,
e.g. Area meter x meter, or m2 Volume meter x
meter x meter, or m3
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Measurement
Quantitative measurements or numerical data
(singular datum) are always preferred in
scientific observations because
To be valid, all observations must be repeatable
(replicable) by other observers

• they allow variation in the observations to be
  described

• they permit statistical methods of data analysis
  to be applied that may help to understand the
  data, confirm its validity and convince others

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Hypotheses predictions
Start with a question what, how, why, when,
how often, how much?
about the observation (s)
and suggest a possible answer that can be
investigated
An example
Some caterpillar species are brightly coloured
and appear to be conspicuous to predatory species
such as insectivorous birds
Why dont they get eaten? Why do they seem to
occur in groups? How do birds behave towards
them? What purpose do the colours serve? How
could this phenotype have evolved? and so on
Suggest a hypothesis to explain why some
caterpillars are brightly coloured and
conspicuous while others are cryptic and blend
into their surroundings
Suggest an experiment to test your hypothesis
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For every hypothesis, there is a corresponding
NULL HYPOTHESIS (H0) against the predictions
made in the hypothesis
Null Hypotheses

• Scientific hypotheses are expressed in the null
  form of no difference, change, effect or trend
  because it is easier to apply statistical tests
  that can reject H0 in favour of the alternative
  hypothesis supported by the predictions

Experiment
Tests the predictions made by the hypothesis and
may lead to identification of a need or direction
for further observation
Data collection by means of

• Laboratory experiments and tests
• Field experiments and surveys
• Carefully defined and specified observations

must be carefully planned to ensure observations
and measurements ..
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Null Hypotheses

• record the right type of information including
  factors which may affect the values of data or
  events being recorded (sources of error )
• are accurate the observed value agrees closely
  with the true value,not influenced by
• human errors e.g. misreading of instruments,
  mistaken recording, rounding errors
• instrument errors e.g. systematic errors in a
  scale reading introducing bias
• are precise repeated observations agree with
  each other
• are recorded in an organised way that will not
  lead to confusion at a later time, e.g. failure
  to label data or state units of measurement
• are bias-free not affected by recorder choice
  or presence but truly random observations that
  are representative of the bigger picture, e.g.
  whole population

Standardisation of experimental method is
crucially important!!
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Experiments are often designed in a way that fix
or control variables that may affect the
observations being made
Variables

• This usually involves keeping them constant, e.g.
  light level, temperature, volume of reactants,
  container size etc

The dependent variable is the response that is
being observed and recorded
The independent variable is the influencing
factor under investigation
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The Publication of Research
There's not much good in finding out things if
no-one knows what you have discovered!

• A structured scientific report must include the
  following components / sections
• A TITLE
• An ABSTRACT
• An INTRODUCTION
• A MATERIALS METHODS section
• A RESULTS section
• A DISCUSSION and interpretation of the results
• ACKNOWLEDGEMENTS

• A BIBLIOGRAPHY

All scientific reports must be written in the
third person and in the past tense