the scientific knowledge we have today has been developed largely by subjecting hypotheses to strict and comprehensive testing. a hypothesis is a possible explanation for an observation, an educated guess to account for what is observed. when a hypothesis is tested under controlled conditions, the experimental results either support or disprove the hypothesis. when a hypothesis is supported by experimental data it does necessarily mean that it will always hold true. later evidence may disprove the hypothesis or provide new information that means the original hypothesis needs to be modified and retested.
a controlled experiment involves setting up two trials, the same in every respect except one: the factor being examined. this factor is often called the experimental variable or simply the variable. in one trial, all factors are kept constant while measurements are taken. this set-up is called the control. in the other trial, one factor is varied. this will ensure that any results obtained are the results of the variable being tested, and not caused by some other random factor. that is, controlled experiments test one factor at a time.
the reliability of testing does not just lie in the setting up of a single controlled experiment. experiments must be able to be conducted repeatedly with the same results. when the same results are obtained repeatedly by following the same procedures, the hypothesis being tested is supported further. repetition, especially by other scientists, is an important part of ensuring reliability in scientific testing. this because when the same results are obtained the objectively of the experiment is reinforced.
scientists must be very careful to ensure that personal bias does not enter into their experimental method. valid conclusions can only be made when experimental procedures are controlled and objective (controlled links back to controlled experiments and objective means not influenced by personal feelings or opinions.)
EXPERIMENTAL DESIGN:
real biological investigations often evolve as a result of a great deal of trial and error. they rarely start with logically developed 'step by step' procedures and clearly formulated recipes.
the description that follows outlines a possible sequence of events in designing an experimental investigation:
scientific inquiry:
with only slight modifications, the approach to scientific inquiry described below will help you to design scientifically sound (means extra research for me) experiments.
making an observation:
scientific inquiry starts when you make an observation about something.
asking a question:
ask a question or questions about the observation.
formulating a hypothesis:
a hypothesis is a simple statement that attempts to answer a question--it is not itself a question. a good hypothesis is really an educated guess, and it should be testable by experimentation.
designing an experiment:
when you have considered a suitable approach you should write out a step-by-step account of how you will proceed. in this instance you will also need to design a choice chamber in which to test your hypothesis. this should be relatively simple to do.
controlling variables:
in this experiment, slaters are given a choice between wet and dry conditions. in order to be certain that the slaters are really making a choice only between these two options, all other conditions must be identical (for example, just one plant pot and if show these two options might be cause by random factor get two and then is more reliable).
humidity is the experimental (or independent) variable, the one you are manipulating, and the behaviour of the slaters is the responding (or dependent) variable. this is the one that changes in response to the variable that is manipulated. all the other conditions that do not change but could are called fixed (or constant) variables.
it is essential that only one variable at at time is manipulated.
CARRYING OUT THE EXPERIMENT:
follow each step of the procedure you have designed.
recording data:
ensure that you record all the relevant data as you go. this includes any measurements and / or observations you make.
summarising results:
this involves analysing the data you have collected and writing a summary statement. attempt to explain any unexpected results.
evaluating experimental procedure:
outline the strengths and weaknesses of your experimental design, then describe the ways in which your procedure could be improved.
making a concluding statement:
make a concluding statement about your results in relation to the hypothesis you set out to test. did your results support the hypothesis?
WRITING REPORTS:
accurate record-keeping is a vital part of the scientific process. it enables other scientists to read, analyse and repeat the experimental procedures that have been undertaken by their peers. it is particularly important when the results of experiments can have an impact on the well being of the community, such as in the development of medicinal drugs. no one in the community would be satisfied about the safety of a drug if the research scientist have committed the test results to memory instead of to paper or the microchip.
title: an appropriate name for the exercise conveys information about the topic being discussed.
purpose (aim in relation to designing experiments): a brief statement outlining what is being investigated, what you are setting out to discover, should be provided. some experiments require you to investigate more than one aspect of the topic. in this book each item under investigation is outlined in a separate statement under the purpose (equipment in relation to designing experiments).
materials: all items of laboratory equipment, chemicals, specimens and miscellaneous materials that are used in the completion of the activity should be listed.
procedure: the steps followed in completing practical activities must be carefully catalogued. a step by step approach is a useful way of producing a description of your method. a summary of your procedure is especially important to have as a reference when their is doubt about experimental error. it is also a clear recipe for others to follow if required.
results and discussion: a summary of your experimental findings, together with your conclusion, forms the basis of your practical work. the discussion should contain a clear description of the results of your experimentation. this may be done in a range of forms, for example, in a written synopsis or in a table or in graphic form. analysis and interpretation (like for example a table--what should this finding be placed under etc) is an important feature of this section of your report.
answers to set questions also form part of the discussion. often the set questions help you to describe and interpret experimental results. drawings and diagrams are also included in the discussion section of your report.
other comments that you wish to make, including factors that have limited your work, are relevant here. so too are suggested explanations for unusual or unexpected results(these do not necessarily indicate error or flawed procedure).
conclusion: this is a statement outlining the results of your investigation. it should state what you discovered in relation to your purpose (so has to relate somewhat to your hypothesis--an educated guess, an answer to an observation). the conclusion is often covered by the discussion questions so it is not necessarily written as a seperate section.
DISCLAIMER: I DO NOT OWN THESE NOTES ALL RIGHTS BELONG TO THEIR OWNER: THE AUTHOR OF MY WORKSHEETS, THE AUTHOR OF MY BROUGHT, GIVEN OR BORROWED TEXTBOOKS.
AND LASTLY, THE WORKS GIVEN FROM MY SCIENCE TEACHER.
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