“We make a living by what we get, but we make a life by what we give.” – Winston Churchill
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Monday, December 23, 2013
Introduction to Experimental Design
Not all experiments are performed under laboratory conditions; many occur outdoors in uncontrolled conditions. Scientists must account for these variations when designing experiments.
Controlling all variables but one ensures that some other factor is not responsible for the results obtained from an experiment.
An experiment could not be designed to test this statement. Science neither supports nor rejects this idea.
A hypothesis is supported or rejected based on the outcome of one or more experiments.
By using a swan-necked flask for the experimental treatment, Pasteur ensured that no cells were entering the flask from the air. Thus, any organisms that appeared in the experimental flask would have arisen spontaneously.
Pasteur boiled the broth to kill any existing organisms, thus ensuring that the conditions in each flask were identical (i.e., lacking organisms) at the start of the experiment.
This experimental group tests the effects of wing waving alone.
This result suggests that the presence or absence of wing surgery itself may affect the jumping spider's responses. Thus, there is not enough information to draw conclusions from the data because there is an alternative explanation for the results of the experiment.