2005_campbl01c

# 2005_campbl01c - Chapter 1c: Exploring Life (section 1.5,...

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1 Chapter 1c: Exploring Life (section 1.5, first lab) Experimentation ¾ Asking Good Questions ¾ Forming Hypotheses ¾ Testing Hypotheses ± As you can see by our continued emphasis of this third section on “testing hypotheses,” a great deal of a scientist’s time is spent hypothesis testing rather than hypothesis making ± This is why the caricature of scientists is a person in a lab coat working at a bench ¾ Asking Good Questions ¾ Forming Hypotheses ¾ Testing Hypotheses ± As you can see by our continued emphasis of this third section on “testing hypotheses,” a great deal of a scientist’s time is spent hypothesis testing rather than hypothesis making. ± This is why the caricature of scientists is a person in a lab coat working at a bench. ± "The most creative aspect of science is designing a test of your hypothesis that will provide unambiguous evidence to falsify or support a particular explanation… ± …Scientists often design, critique, and modify a variety of experiments and other tests before they commit the time and resources to perform a single experiment."

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2 Variables ± To understand how to successful perform experiments, one must understand how to successfully handle (and describe) variables ± A poorly run experiment often is as much a consequence of poor technique as a consequence of failure to properly identify and control variables ± We can divide variables into three general types: Independent Variables Dependent Variables Controlled Variables ± Your goal will be to distinguish between and otherwise not confuse these three variable types Dependent Variable ± Within an experiment, the dependent variable is that which is being measured, the variable that you hypothesize will change as a function of change in one or more independent variables ± Very often varying an independent variable will result in more than one measurable change in the system ± Consequently, it is routine for an experiment to have more than one possible dependent variable , though doing so will often increase the size and complexity of an experiment Employing Dependent Variables ± If we were determining the effect of sunshine on plant growth, then some measure of plant growth would represent the dependent variable ± The hypothesis in this case may have been something to the effect of, “Exposure to sunshine causes plants to grow.“ ± Note that in order for this to be an effective experiment, the dependent variable must be measurable, the more precisely the better ± This need for measurability is what makes the "supernatural" off limits to science since the supernatural, by definition, is not a measurable quantity Independent Variable ± The independent variable is that measure that is being purposefully varied in the course of an experiment to test whether such variation results in a change in the dependent variables ± For example, if we were determining the effect of sunshine on plant growth, then the degree to
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## This note was uploaded on 06/03/2011 for the course BIO 113 taught by Professor Swenson during the Spring '08 term at Ohio State.

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2005_campbl01c - Chapter 1c: Exploring Life (section 1.5,...

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