Transcript Identifying Independent and Dependent Variables

Identifying Independent and
Dependent Variables
August 17, 2010
Biology I
Page 45 SATP Workbook
Important Terms to Know
• Experiment-a set of steps that are performed to
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collect data.
Control group- stands as a standard for
comparison
Experimental group- group that receives the
treatment, drug, something ‘special’
Placebo-an inert (fake or inactive) substance
that is usually given to the control group
Important Terms to Know
• Independent Variable – what the
experimenter uses or changes
• Dependent Variable – what is measured in
an experiment.
These are some questions that should be
considered when setting up an experiment
• What data should be
• Will there be a
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collected and how?
How many groups will
be used?
How many
subjects/people per
group should be used
What will be the
control group?
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placebo used?
What are the
important constants?.
What is the
independent variable?
What is the
dependent variable?
Tips on helping identify hypothesis,
IV, DV, ect.
• The hypothesis is usually presented in an “If-
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Then” statement. If not, it will show what
someone ‘thinks’ will happen. Sometimes it is
the first sentence in a paragraph.
In most written experiments, you can find the
independent variable and the dependent variable
in the first sentence.
In graph form, the independent variable is on
the X-axis, and the dependent variable is on the
Y-axis.
Example
• Waldo wants to determine which fertilizer,
X, Y, or Z, will cause corn plants to grown
the fastest. He thinks that the corn plant
that receives brand Y will grow the fastest
because it contains the most phosphorous.
• Identify the IV, DV, and the hypothesis.
Example pg 48
• A pharmaceutical company gets FDA
approval to test a memory enhancing drug
on humans. The company chooses 100
participants and split them into two groups
of 50 each. Once a day and over a period of
6 months, each participant is given a pill. In
one group, the pill contains the medication.
IN the other group, the pill contains no
active ingredient. Once a week, the
participants are given a test that measures
their memory. The score for the test is
recorded for each participant each week.