_____
_____
_____
_____
____
Name:
Date:
Experimental Design: Writing Hypothesis
ixample 1
A researcher is studying the effect of sleep on aggression, thinkin
g that less sleep will lead to more aggression.
She has Group A people sleep 8 hours per night and Group B people
sleep 3 hours per. She then monitors
aggressive behavior during basketball games among participants.
Research Question: Does the amount of sleep affect aggression?
Hypothesis (‘if...then...because”):
Example 2
A researcher is curious to find out what effect classical music has
on people’s level of relaxation (as measured
by heart rate). He suspects that listening to classical music will
make people feel more calm and relaxed. He
lets one group (A) listen to classical music for one hour. He lets anothe
r group (B> sit in a quiet room for one
hour (i.e they hear no music). After one hour, he monitors the heart
rate of each participant to measure their
level of relaxation.
Research Question: Does classical music have an effect on people
’s relaxation?
Hypothesis (“lf...then...because”):
Example 3
A famous botanist wanted to determine the effect of colored lights
on plant growth. She noticed that a plant
kept under blue fluorescent lights grew better than a plant kept in
natural light in her green house. She took a
year old geranium plant and placed it in natural light in her green
house. She also took another year old
geranium and placed it in her house under blue fluorescent lights.
She watered them every other day and
fertilized them once a week. After 3 weeks she checked the height
of the plants in both lights.
Research Question: Does colored light affect plant growth?
Hypothesis (“lf...then...because”):
Example 4
A researcher wants to find out if the bacteria growing is antibio
tic resistant. She takes the bacteria and places
some of it on a petri dish with normal agar. She takes the rest of
the bacteria and places some of it on a petri
dish with agar that contains antibiotic. She places both petri dishes
in an incubator overnight. The next day
she counts the amount of colonies that have or have not grown on
both plates.
Research Question: Do antibiotics affect the growth of bacteria?
pothesis (“lf...then...because”):
_____________
Name
Date
Experimental Design Practice
Example 1
A researcher is studying the effect of sleep on aggression, thinking that less sleep will lead to
more aggression. She has Group A people sleep 8 hours per night and Group B people sleep 3
hours per. She then monitors aggressive behavior during basketball games among participants.
Identify:
•
The Control Group/Set up
•
The Experimental Group/Set up
•
Two Control Variable(s)
•
The Independent Variable
•
The Dependent Variable
—
—
—
-
-
Example 2
A researcher is curious to find out what effect classical music has on people’s level of relaxation
(as measured by heart rate). He suspects that listening to classical music will make people feel
more calm and relaxed. He lets one group (A) listen to classical music for one hour. He lets
another group (B) sit in a quiet room for one hour (i.e they hear no music). After one hour, he
monitors the heart rate of each participant to measure their level of relaxation.
Identify:
•
The Control Group/Set up
•
The Experimental Group/Set up
•
Two Control Variable(s)
•
The Independent Variable
•
The Dependent Variable
—
—
-
-
—
Example 3
A famous botanist wanted to determine the effect of colored lights on plant growth. She noticed
that a plant kept under blue fluorescent lights grew better than a plant kept In natural light in
her green house. She took a year old geranium plant and placed it in natural light in her green
house. She also took another year old geranium and placed it in her house under blue
fluorescent lights. She watered them every other day and fertilized them once a week After 3
weeks she checked the height of the plants in both lights.
Identify:
•
The Control Group/Set up—
•
The Experimental Group/Set up
•
Two Control Variable(s)
s :ot
—
•
The Independent Variable
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-
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-
•
The Dependent Variable
unt
-
Example 4
A researcher wants to find out if the bacteria growing is antibiotic resistant She takes the
bacteria and places some of it on a petri dish with normal agar. She takes the rest of the
bacteria and places some of it on a petri dish with agar that contains antibiotic. She places both
petri dishes in an incubator overnight The next day she counts the amount of colonies that
have or have not grown on both plates.
Identify:
•
The Control Group/Set up
•
The Experimental Group/Set up
•
TwoControl Variable(s)—
•
The Independent Variable
•
The Dependent Variable
Vii
-
cniiWc ñ (3
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-
t’j.
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-
—
Ct
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.
__
Types of
___
Variables
Dep
dent
Controued
The one thing
you change.
Limit to only one
in an experiment.
The change that
happens because
of the
independent
variable.
Everything you
want to remain
constant and
unchanging.
Example:
The liquid used to
water each plant.
Example:
The height or
health of the plant.
Example:
Type of plant used,
pot size,
amount of liquid,
soil type, etc.
Independent
Variable
Dependent
Variable
Controlled
Variables
I
p
I
I
•3
I
ControlGroip (or Control “set-up”) The group of individuals (or the set-up if you are not
working with people) which is NOT being tested and is subjected to normal/regul
ar
conditions; used for COMPARISON
-
Experimental Group (or Experimental “set-up”) The group of individuals (or
the set-up if
you are not working with people) which IS being tested and is subjected to altered/specia
l
conditions
-