Transcript Slide 1

The Scientific Method
Introduction
The scientific method is probably
the most fundamental skill
process in the world of science.
From the beginning of our
existence, humans have been
curious as to why and how things
happen in the world around us.
The scientific method provides us
a structured scientific platform to
help us find the answers… With
the scientific method, the sky is
the limit!
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Scientific Method
Process that provides scientific knowledge.
Process involves:
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Observing phenomena
Asking a question
Conducting background research
Planning an investigation
Predicting and hypothesizing
Testing hypothesis by doing an experiment
Analyzing and evaluating results
Drawing up conclusions
Communicating your findings
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Observing Phenomena
We are observing various
biological systems, relationships
and phenomena happening
around us all the time.
The observations one can make
are endless and range anything
from:
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Physiological observations noticing your heart rate increase
when you are nervous to…
Ecological observations - the
relationship between predator and
prey in a particular habitat.
Observations naturally lead onto
questions about the phenomena
being observed.
An electrocardiogram
(ECG) measures the
heart’s electrical activity.
It is important to keep an eye on populations
of species within a community.
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Asking a Focus Question?
We have a problem/question and we need to find a solution/answer.
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Does the heart beat faster under stressful conditions?
What happens to a predator’s population after a long period of drought?
Sometimes these are broad questions that need to be narrowed down
into focus/research questions which are more specific.
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Conducting Background Research
Become informed on the topic of your
research.
Q: Does the heart beat faster under stressful
conditions?
→ You may then research how the heart
functions? How heart rate is measured?
How it speeds up and slows down? And
what determines a physiological stressful
situation?
Q: What happens to a predator’s population
after a long period of drought?
→ You may then research what defines a
drought? How drought affects
ecosystems? What are the factors that
affect cheetah populations?
Scientific journals are a good
place to start doing background
research.
Background research also helps narrow
broad questions into focus/research
questions.
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Planning an investigation
A written part of the scientific method. Use a checklist or template
to plan your investigation as shown below:
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Planning an investigation
If necessary a scientist
needs to consider other
factors for the
investigation such as:
→A
Moral and ethical considerations are important in all scientific
research. Research ethics can be described as: “the application
of moral rules and professional codes of conduct to the
collection, analysis, reporting, and publication of information
about research subjects, in particular active acceptance of
subjects' right to privacy, confidentiality, and informed consent”.
(Marshall 1998)
literature review on all
the background research.
→ A research proposal.
→ Funding of the
investigation/research.
→ Moral and ethical
considerations.
→ Conducting a pilot study.
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Forming a Hypothesis and/or and Aim
As you begin planning your investigation you
need to form a hypothesis and an aim based on
your observations.
→ It
is important to recognize the difference between an
aim and a hypothesis.
→ It doesn’t really matter which you form first.
→ When it comes to reporting your investigation
sometimes it is not required for you to write both a
hypothesis and an aim.
→ The key is to check with your teacher as to what is
required.
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Forming a Hypothesis
A hypothesis is a possible explanation to an observation that can be
supported through experimentation.
Educated statement as to your prediction of the outcome of the
investigation.
All good hypotheses should…
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be written as a statement and not a question.
be testable through experimentation.
be falsifiable.
be based on observations and prior knowledge (educated).
give an explanation to an observation.
state the independent and dependent variables.
refer to only one independent variable per hypothesis.
lead to further predictions about the system being investigated.
Q: Does heart rate increase in teenagers
after a physiologically stressful
situation such as running the 100m
sprints?
Q: What happens to the cheetah
population in the Tankwa Karoo
National Park after 2 successive
droughts?
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The Aim… what’s the difference
The aim is usually what you intend on investigating.
Hypothesis is a prediction of the outcome of the investigation.
Aims can vary and don’t necessarily have to relate to the hypothesis.
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Your hypothesis may be something like: Eating 100g of chocolate every
day for 3 months will increase the number of pimples counted on the face
of teenagers aged between 13 – 16 years.
Your aim could be as simple as:
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Your aim could be broader within your scientific report:
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To investigate the relationship between the amount of chocolate being eaten over
a 3 month period with the number of pimples counted on the face of teenagers
aged between 13 – 16 years.
To report the findings of an investigation relating to eating chocolate and the
formation of pimples and to then do a systematic review on the self esteem issues
surrounding teenagers and skin blemishes.
Your aim could be broken down into specific aims within your
investigation such as:
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To determine a classification system for distinguishing pimples from other skin
blemishes.
To obtain as many signed consents for the investigation’s sample group.
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Writing an Aim
Some ways of wording an aim are:
To determine...
→ To show that...
→ To investigate...
→ To find out...
→ To observe...
→ To measure...
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Do not write ‘To prove...’ because not only will your
investigation more than likely not get to this stage, but
also because many scientists believe that nothing is
proven absolute.
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Variables
Variables are factors that are subject to
variation/change.
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Identify the variables that you could possibly
change.
Identify all the variables that you could
measure/observe.
Choose one variable that you can change or
manipulate (independent variable) in the
investigation that will have an affect on variables
that you can measure/observe (dependent
variables).
All the other variables that you identified you need
to control (fixed/controlled variables) so that you
are changing only one variable at a time.
Not to be confused with the scientific ‘control’ of an
experiment which is an experiment that is done in
addition to the test experiment but in which the
independent variable, the variable that the researcher is
changing, is removed. This reinforces that the cause of
the change in the dependent variable is due to the
independent variable only.
Variables are factors that are subject
to change. Dependent variables are
variables we can measure or
observe.
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Identify the variables
Increased light intensity will increase the
growth rate of pelargonium's.
Higher salaries are earned after more
years spent studying in educational
institutions.
Populations living at higher altitudes can
hold their breath for longer under water.
There is a decrease in heart attack frequency in adults who spend more
time doing cardiovascular exercise.
Bacterial growth rate increases as environmental temperature increases.
Teenagers eating foods high in saturated fats increase the probability of
atherosclerosis in later adult life.
More students are diagnosed with influenza during exam time than during
other times in a school calendar.
Soils with a higher clay composition decrease the root length of protea’s.
As temperature rises in Cape Town, reported crimes to the police increase.
The number of people who exercise daily increases during the summer
months than during the other months of the year.
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Variables in Graphs and Tables
Independent Variable:
Manipulated by the researcher.
Recorded on the X-axis of the graph.
Recorded on the right hand side of the table.
Table Heading
X-axis data (units)
Y-axis
Graph Heading
X -axis
Y-axis data (units)
Dependent Variable:
Measured during the investigation.
Recorded on the Y-axis of the graph.
Recorded on the left hand side of the table.
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Variables and Data
Data are the values that are collected from observed or
measured variables.
There are various types of data that effect the way we
collect and report our investigation.
Types of Data:
Qualitative Data = descriptive data, non-numerical (e.g.
colour, names, sex, absence or presence).
→ Quantitative Data = numerical data, measurements or
counts can be made (e.g. height, mass, length, number)
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→ Continuous data
= data that has joined values or in between
values (e.g. height: 1.5m – 2.2m).
→ Discontinuous data = values that are discrete from one another, no
in between values (e.g. number of children in a class: 23, 24, 25)
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Testing Hypotheses
Once variables have been identified, you need
to decide how these variables will be set and
measured.
You need to be clear on the type and quantity
of data that you collect.
Written stages of an investigation:
→ Planning the investigation.
→ Reporting the investigation.
Practical stages of an investigation:
→ Laboratory
work.
→ Field work (natural system).
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Testing Hypotheses
Setting up IV:
Change light intensity = different
quantities of shade cloth,
placing pelargonium’s in
different parts of a
greenhouse….
Increased light intensity will increase
the growth rate of pelargonium's.
Important!
‘Rate’ means that time
must be involved. How can
you ensure that you
measure a growth rate?
Measuring DV:
Height/Time = use a measuring
tape, use a ruler or placing a
wooden rod next to plant
and marking height at set
time intervals.
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Testing Hypotheses
Measuring DV:
Amount of money = Survey
question asking to tick the
appropriate income bracket.
Higher salaries are earned after more years
spent studying in educational institutions.
Setting up IV:
Years spent studying = Survey seems
to be the easiest way to get this
type of data – “How many years did
you spend studying in
educational institutions?”
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Testing Hypotheses
Setting up IV:
Altitude = in this example your
sample groups are important. You
will need to test various
sample groups living at
different altitudes.
Populations living at higher altitudes can hold their
breath for longer under water.
Measuring DV:
Time = simple stopwatch can
be used to collect this
data.
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Testing Hypotheses
There is a decrease in heart attack frequency in adults who spend more
time doing cardiovascular exercise.
Bacterial growth rate increases as environmental temperature increases.
Teenagers eating foods high in saturated fats increase the probability of
atherosclerosis in later adult life.
More students are diagnosed with influenza during exam time than during
other times in a school calendar.
Soils with a higher clay composition decrease the root length of protea’s.
As temperature rises in Cape Town, reported crimes to the police increase.
The number of people who exercise daily increases during the summer
months than during the other months of the year.
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Doing an Experiment
You’ve decided on how
you want to test your
hypothesis including
how you are going to
collect your data.
Two things to consider
before doing an
experiment are:
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Setting up a Polymerase Chain Reaction
(PCR) in a biomedical laboratory.
Sample Size
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important
when doing field work.
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Replication
Laying out transects to investigate ant
populations.
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Sample Size
Sample size (n) is the number of
sampling units being investigated
within any given population.
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Sampling units for example could
be the number of individual
organisms, transects or quadrants.
Always best to try and take as
many samples as possible.
This way you have a better
representation of the population.
→ It accounts for any natural
variability that may be present in
your sample groups.
→ You can have greater confidence in
your data.
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An investigation may be on a
population of impala (above)
so a sample group (right) n=
3 was selected to be studied
as a representation of the
impala population.
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Replication
Replication refers to the number of times you repeat your
entire experimental design (including controls).
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This improves the reliability of your results.
Increasing your sample size doesn’t necessarily mean you’ve
replicated the experiment more times.
Water Regime:
0ml water/day
@ 15°C, pH 7
(control)
Water Regime:
500ml water/day
@ 15°C, pH 7
Water Regime:
1000ml
water/day @
15°C, pH 7
Water Regime:
0ml water/day
@ 15°C, pH 7
(control)
Water Regime:
500ml water/day
@ 15°C, pH 7
Water Regime:
1000ml
water/day @
15°C, pH 7
The experiment to
the left has been
repeated only
twice.
The sample size
(n) = 3
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Results: Constructing Tables
Tables are quick effective way of organizing numerical values making
relationships and trends apparent.
Well constructed tables follow certain rules:
Table 1: A table showing a summary of the blood plasma levels of four
hormones in astronauts before and after the Apollo space missions (Adapted
from Leach & Alexander 1975).
Hormone
n
Preflight
(mg/100ml)
Postflight
(mg/100ml)
Percent
change (%)
Control
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4.7
4.8
+2
Thyroxine (T4)
30
6.8
7.6
+ 12
Tri-iodothyronine (T3)
22
32.4
32.1
-1
Insulin
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6.8
9.0
+ 32
Human Growth
Hormone
10
2.6
3.5
+ 35
*n = number of astronauts investigated.
5) Independent variable to
the left of the table.
4) Dependent variable to the
right of the table.
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Results: Constructing Graphs
Graphs are very effective at representing relationships and trends visually
in a small amount of space.
Drawing well constructed graphs you need to follow certain rules:
2) A descriptive, accurate heading
which is numbered throughout a
report (called figure).
9) Graph
must be at
least ½ page
in size.
Figure 1: A bar graph showing the heart rate change of test subjects
before and then after doing the 100m sprints.
7) X axis: Independent variable, labeled with
units if applicable, scale evenly distributed.
4) Bars, lines in
pencil.
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Analysis of Results
Results are collected firstly in the field or laboratory as raw data.
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It is always wise to draw up a table before doing your investigation to collect
your raw data.
After raw data has been collected it must be transformed to be analyzed
and then evaluated.
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Transformation of raw data is important for this process as it helps to pick up
trends and relationships.
Transformation usually takes place in a table where averages, totals,
percentages, rates and relative values can be worked out.
Table of raw data collected showing the heart rate in
beats per minute (bpm) of test subjects before and
after they were subjected to the 100m sprints.
Before
(bpm)
Subjects
(S)
Table showing the heart rate change of test subjects
before and then after doing the 100m sprints.
After
(bpm)
S1
55
132
S2
48
119
S3
42
127
Transform raw data
Subjects Before
(bpm)
(S)
After
(bpm)
Difference
(bpm)
S1
55
132
+77
S2
48
119
+71
S3
42
127
+85
Average
48
126
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Analysis of Results
As Scientists we need to learn the skill of reading
trends and inferring relationships between variables.
Table 1: The average time of a Grade 10 biology class to
complete the same biology test on 4 different attempts.
Time (min)
Attempt number
Attempt 1
38
Attempt 2
29
Attempt 3
27
Attempt 4
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Table 2: The effect of different fertilizers on the growth rate of tomato plants
over a 28 day period.
Tomato plant height (cm) taken at 7 day
intervals
Fertilizer
group
Day 0
Day 7
Day 14
Day 21
Day 28
Total
growth
Control
10
23
38
44
52
42
Fertilizer A
11
25
52
63
72
61
Fertilizer B
9
23
40
48
55
46
Fertilizer C
10
24
42
50
60
50
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Analysis of Results
As X increases, Y
increases = Directly
related.
As X increases, Y
stays constant/the
same.
As X increases, Y
decreases = Inversely
related.
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Analysis of Results
T
S
R
A
B
C
V
T
S
U
RA
B
C
D
E
F
G
H
D
As A changes to B there is a
steep increase from value R to S.
From B to C value S increases at a
less and less gradient to a maximum
value T. As C changes to D then E,
Value T decreases back to S
finally ending at starting value
R.
E
As A changes to B, value R
steadily increases up to T. From B to C,
value T remains constant until there is a
slight decrease to value S as C changes
to D. There is then a more steeper
decrease as D changes to E. At value E
there is a turning point and U increases
steadily up to value V at point F. From F
to G Value V remains constant until it
decreases back down to value R as G
changes to H.
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Evaluating Results (Discussion)
In written section of investigation
called ‘Discussion’.
After analyzing your results (graphs
and tables) it is important to evaluate
the results.
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What is the worth of the investigation?
What do the results mean?
Were there any outlying/anomalous
results?
Do these findings support other
research?
How was validity and reliability
ensured?
Summarize any experimental errors.
What recommendations can you make
for future research?
Writing a discussion is one of the most
important sections of the scientific report
as it is where the worth of your
investigation can be made clear.
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Validity and Reliability.
Validity:
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The fairness of the experiment.
This is ensured in an investigation
when there are only two variables
being investigated; one input
(independent variable), one
outcome (dependent variable) and
all other variables were kept fixed.
Reliability:
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Validity and reliability are two important
considerations when doing scientific
investigations.
If the experiment was repeated
would similar results be generated?
This is ensured when the
experiment is repeated several
times and often averages are
obtained.
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Drawing up Conclusions
A well constructed conclusion…
→ links the results directly to
the
aim and hypothesis.
→ is written in a short paragraph.
→ includes both what was observed
in the investigation and whether
this supports or rejects the
hypothesis.
→ re-states all variables tested.
Remember, no result , is still a
result and a conclusion must be
given for this.
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Recording a Scientific Investigation
A scientific report is usually done in conjunction with all the steps of
the scientific method.
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Forms the written part of scientific method.
Especially needed after the analysis of results for the discussion
section which then leads onto a well formulated conclusion.
See word doc 10 point guideline on recording an investigation.
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References and Bibliography
Science is all about collaboration and every
individual’s ideas and thoughts are shaped by
others.
Acknowledge any intellectual property (ideas and
information) that does not belong to you.
Not only because of plagiarism but because it is
only fair to attribute those who have contributed
to your investigation.
There are many different referencing formats; you
need to find out which one suits your type of
investigation.
There are TWO main rules for referencing:
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Science is about collaboration
and it is very important to
recognize those who have
contributed to your investigation.
A reference must be included every time you use
someone else’s information or ideas. This includes
every time you paraphrase/summarise (write out
someone else’s intellectual property into your own
words) and quote/copy (reproduce exactly the
same someone else’s intellectual property)
Every reference needs to appear twice, in the text
as well as in the reference list which is found at the
end of the scientific document.
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Communicate your Findings
Scientists must inform other members of the scientific and general
community of their findings to continue the quest for knowledge.
Done through:
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popular publications (newspapers, magazines, radio and television)
scientific publications (scientific journals).
Outstanding achievement when work is published in a peerreviewed academic journal.
Marie Curie, 1903
Nobel Laureate in
Physics for work on
the radiation
phenomenon.
Albert Einstein, 1921
Nobel Laureate in
Physics for work on
theoretical phyics.
South African Max
Theiler, 1951 Nobel
Laureate in
Physiology or
Medicine for
discovering a
vaccination for yellow
fever.
James Watson, 1962
Nobel Laureate in
Physiology or
Medicine for the
discovery of the
molecular structure of
nucleic acids.
South African Sydney
Brenner, 2002 Nobel
Laureate in
Physiology or
Medicine for
discoveries
concerning genetic
regulation and
programmed cell
death.
Saul Perlmutter, 2011
Nobel Laureate in
Physics for the
discovery of the
accelerating
exapansion of the
universe.
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Image Bibliography
Slide 1:
Anon, HowStuffWorks “Scientific Method Applications” [image online]. Hill Street Studios/Getty Images. Available at: http://science.howstuffworks.com/innovation/scientificexperiments/scientific-method8.htm [Accessed November 9, 2011d].
Anon, Question mark [image online]. Available at: http://communicationskillstips.com/2011/questions-you-must-answer-before-your-next-presentation/ [Accessed November 9,
2011k].
Slide 2:
Anon, Sky is the limit [image online]. Available at:
http://www.google.co.uk/imgres?q=sky’s+the+limit&hl=en&sa=X&rlz=1T4SKPT_enZA451GB453&biw=1600&bih=574&tbm=isch&prmd=imvns&tbnid=cLGvTUY5lmMOpM:&i
mgrefurl=http://perfectlypink-randomthoughts.blogspot.com/2010_11_01_archive.html&docid=0wYT7-OHAFgiNM&imgurl=http://2.bp.blogspot.com/_BfpgQVIiH8/TPS2MnjlPTI/AAAAAAAAAPY/GZTDqRoxfi0/s1600/Sky_20is_20the_20Limit.jpg&w=700&h=428&ei=zkK6TrzrJYSV8QPr7dynBw&zoom=1&iact=hc&vpx=484&vpy=278&
dur=78&hovh=175&hovw=287&tx=150&ty=77&sig=113804045632951459688&pag [Accessed November 9, 2011m].
Slide 4:
Anon, How To Measure Your Heart Rate [image online]. Available at: http://goodinfohubs.com/2011/06/how-to-measure-your-heart-rate/ [Accessed November 9, 2011c].
Anon, Cheetahs [image online]. Available at: http://personalpages.warnerpacific.edu/kterwilliger/Cheetahs.html [Accessed November 9, 2011b].
Slide 5:
Wraith, B., Do Things…Without Thinking! [image online]. Available at: http://brandonwraith.com/do-things-without-thinking/ [Accessed November 9, 2011].
Slide 6:
Anon, Nature journal digitises archive [image online]. BBC NEWS. Available at: http://news.bbc.co.uk/1/hi/sci/tech/7138704.stm [Accessed November 9, 2011i].
Slide 8:
HSE, R.R., HSE - Science and research - Research ethics committee [image online]d. Available at: http://www.hse.gov.uk/research/ethics/ [Accessed November 9, 2011].
Slide 13:
Joenn, A., What is Analytical CRM? [image online]. Available at: http://info.collierpickard.co.uk/blog/bid/57523/What-is-Analytical-CRM [Accessed November 14, 2011].
Slide 22:
Authors copyright.
Slide 23:
Grobler, P., 2010. Impala harem | Flickr - Photo Sharing! [image online]. Available at: http://www.flickr.com/photos/oom_piet/5041080076/ [Accessed November 15, 2011].
Slide 31 & 33:
Anon, Paul’s Images - FreeDigitalPhotos.net [image online]. Available at: http://www.freedigitalphotos.net/images/view_photog.php?photogid=1526 [Accessed November 15,
2011j].
Slide 32:
Anon, Key Elements of a Scientific Experiment [image online]. Available at: http://www.ehow.com/info_10049050_key-elements-scientific-experiment.html [Accessed November 15,
2011f].
Slide 35:
Anon, tungphoto’s Images - FreeDigitalPhotos.net [image online]. Available at: http://www.freedigitalphotos.net/images/view_photog.php?photogid=1708 [Accessed November 15,
2011o].
Slide 36:
Anon, Sydney Brenner - Autobiography [image online]. Available at: http://www.nobelprize.org/nobel_prizes/medicine/laureates/2002/brenner.html [Accessed November 15,
2011n].
Anon, Saul Perlmutter - Biographical [image online]. Available at: http://www.nobelprize.org/nobel_prizes/physics/laureates/2011/perlmutter.html [Accessed November 15, 2011l].
Anon, Marie Curie - Biography [image online]. Available at: http://www.nobelprize.org/nobel_prizes/physics/laureates/1903/marie-curie.html [Accessed November 15, 2011g].
Anon, Max Theiler - Biography [image online]. Available at: http://www.nobelprize.org/nobel_prizes/medicine/laureates/1951/theiler.html [Accessed November 15, 2011h].
Anon, James Watson - Biography [image online]. Available at: http://www.nobelprize.org/nobel_prizes/medicine/laureates/1962/watson.html [Accessed November 15, 2011e].
Anon, Albert Einstein - Biography [image online]. Available at: http://www.nobelprize.org/nobel_prizes/physics/laureates/1921/einstein.html [Accessed November 15, 2011a].
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List of References
Leach, C.S. & Alexander, W.C., 1975. ENDOCRINE, ELECTROLYTE, AND FLUID VOLUME
CHANGES ASSOCIATED WITH APOLLO MISSIONS (Sec.3,Ch.1). In Biomedical Results of Apollo.
Bio Technology, Inc., p. 10. Available at: http://lsda.jsc.nasa.gov/books/apollo/s3ch1.htm
[Accessed November 11, 2011].
Marshall, G., 1998. research ethics – Dictionary definition of research ethics |
Encyclopedia.com. Available at: http://www.encyclopedia.com/doc/1O88researchethics.html [Accessed November 8, 2011].
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