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Experimental Design:The Big 4
IV
DV
Control
Constants
IV
Independent variable
IV
Independent variable
Manipulated variable
IV
Independent variable
Manipulated variable
the thing “i” change
IV
Independent variable
Manipulated variable
the thing “i” change
Example: type of fertilizer
IV
in an experiment on the effectiveness of cleaners, brian used 4 different types of cleaner: bleach, windex, vinegar, and water.
IV
in an experiment on the effectiveness of cleaners, brian used 4 different types of cleaner: bleach, windex, vinegar, and water.
IV
DV
dependent variable
DV
dependent variable
Measured variable
DV
dependent variable
Measured variable
The “response” to the change
DV
dependent variable
Measured variable
The “response” to the change
example: plant growth
DV
in an experiment on the effectiveness of cleaners, brian Measured the percentage of residue remaining after each cleaner was applied.
DV
in an experiment on the effectiveness of cleaners, brian Measured the percentage of residue remaining after each cleaner was applied.
DV
Control
used for comparison
Control
used for comparison
usually the “most normal” test group
Control
used for comparison
usually the “most normal” test group
may also be a degree of the iv with “lowest value”
Control
in an experiment on the effectiveness of cleaners, brian used 4 different types of cleaner: bleach, windex, vinegar, and water.
control
in an experiment on the effectiveness of cleaners, brian used 4 different types of cleaner: bleach, windex, vinegar, and water.
control
constants
stay the same
constants
stay the same
prove the effectiveness of the iv
constants
stay the same
prove the effectiveness of the iv
look for values that are held “constant” for each test group
constants
brian set up 4-2 in2 tiles. he labeled the tiles a,b,c, and d. Each tile was submersed in a 1:1 mixture of motor oil and tar for 30 sec. they were then allowed to dry for 24 hrs. brian then poured 50 ml of each cleaner on the appropriate tile and wiped the tile 1 time from top to bottom with a clean 4 in sponge.
constants
brian set up 4-2 in2 tiles. he labeled the tiles a,b,c, and d. Each tile was submersed in a 1:1 mixture of motor oil and tar for 30 sec. they were then allowed to dry for 24 hrs. brian then poured 50 ml of each cleaner on the appropriate tile and wiped the tile 1 time from top to bottom with a clean 4 in sponge.
constants
independent variable
dependent variable
#1 The responding variable in an experiment is the...
independent variable
dependent variable
#1 The responding variable in an experiment is the...
control
constant
#2 the test group that is used for comparison is the...
control
constant
#2 the test group that is used for comparison is the...
controls
constants
variables
#3 factors that are kept the same in an investigation...
controls
constants
variables
#3 factors that are kept the same in an investigation...
