the scientific method introduction to the scientific method
TRANSCRIPT
The Scientific Method
Introduction to 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
The Scientific Method
Lecture 1: Introduction to the Scientific Method
1. Observation2. Hypothesis3. Prediction4. 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
Quantitative — 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
Lecture 1: Introduction to the Scientific Method
The Four Steps
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
Basic Units
Physical Quantity Name of Unit Symbol Length meter m
Mass kilogram kg
Time second s
Electric current ampere A
Temperature Kelvin ºK
Luminous intensity candela cd
SI MultipliersMultiplier Prefix Symbol
109 giga G
106 mega M
103 kilo k
102 hecto h
10 deka da
10-1 deci d
10-2 centi c
10-3 milli m
10-6 micro μ (mu)
10-9 nano n
10-12 pico p
Conventionally, indices are used to denote the multiplier
Lecture 1: Introduction to the Scientific Method
Measurement
To be valid, all observations must be repeatable (replicable) by other observers
Quantitative measurements or numerical data (singular datum) are always preferred in scientific observations because:
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
Lecture 1: Introduction to the Scientific Method
Measurement
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
Lecture 1: Introduction to the Scientific Method
Hypotheses & predictions
Why don’t 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
Some caterpillar species are brightly coloured and appear to be conspicuous to predatory species such as insectivorous birds
Suggest an experiment to test your hypothesis
An example
For every hypothesis, there is a corresponding NULL HYPOTHESIS (H0) against the predictions made in the hypothesis
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
ExperimentTests the predictions made by the hypothesis and may lead to identification of a need or direction for further observationData 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 ……..
Lecture 1: Introduction to the Scientific Method
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!!
Null Hypotheses
Lecture 1: Introduction to the Scientific Method
Experiments are often designed in a way that fix or control variables that may affect the observations being made
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 recordedThe independent variable is the influencing factor under investigation
Variables
Lecture 1: Introduction to the Scientific Method
The Publication of Research
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
All scientific reports must be written in the third person and in the past tense
There's not much good in finding out things if no-one knows what you have discovered!
Lecture 1: Introduction to the Scientific Method
► A BIBLIOGRAPHY