variables in an experiment. # of variables in an experiment in any experiment, you only want one...
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Variables in an Experiment
# of Variables in an Experiment
• In any experiment, you only want one variable that you vary from one group to the other.
TrialWeight
(g)Length of String
(cm)Distance pulled
back (cm)# of swings in
60 seconds
Average Swings
1 14.7 50 30 68
69.2
2 14.7 50 30 70
3 14.7 50 30 71
4 14.7 50 30 69
5 14.7 50 30 68
1 49.3 50 30 72
70.4
2 49.3 50 30 70
3 49.3 50 30 69
4 49.3 50 30 71
5 49.3 50 30 70
The Variable you Manipulate
• The variable you want to have different between groups is called the independent variable.
TrialWeight
(g)Length of String
(cm)Distance pulled
back (cm)# of swings in
60 seconds
Average Swings
1 14.7 50 30 68
69.2
2 14.7 50 30 70
3 14.7 50 30 71
4 14.7 50 30 69
5 14.7 50 30 68
1 49.3 50 30 72
70.4
2 49.3 50 30 70
3 49.3 50 30 69
4 49.3 50 30 71
5 49.3 50 30 70
The Variable you Measure• There is another important variable, and this is
the one you measure and expect to be different between groups.
TrialWeight
(g)Length of String
(cm)Distance pulled
back (cm)
# of swings in 60
seconds
Average Swings
1 14.7 50 30 68
69.2
2 14.7 50 30 70
3 14.7 50 30 71
4 14.7 50 30 69
5 14.7 50 30 68
1 49.3 50 30 72
70.4
2 49.3 50 30 70
3 49.3 50 30 69
4 49.3 50 30 71
5 49.3 50 30 70
The Variable you Measure• This variable, the one you measure and expect
to be affected by the independent variable is called the dependent variable.
TrialWeight
(g)Length of String
(cm)Distance pulled
back (cm)
# of swings in 60
seconds
Average Swings
1 14.7 50 30 68
69.2
2 14.7 50 30 70
3 14.7 50 30 71
4 14.7 50 30 69
5 14.7 50 30 68
1 49.3 50 30 72
70.4
2 49.3 50 30 70
3 49.3 50 30 69
4 49.3 50 30 71
5 49.3 50 30 70
The Variables you Control• Any other variables in your experiment can be a
problem. We do what we can to eliminate or control them by keeping them the same.
TrialWeight
(g)Length of String
(cm)Distance pulled
back (cm)
# of swings in 60
seconds
Average Swings
1 14.7 50 30 68
69.2
2 14.7 50 30 70
3 14.7 50 30 71
4 14.7 50 30 69
5 14.7 50 30 68
1 49.3 50 30 72
70.4
2 49.3 50 30 70
3 49.3 50 30 69
4 49.3 50 30 71
5 49.3 50 30 70
The Variables you Control• These bad variables that we don’t want in our
experiment are called confounding variables.
TrialWeight
(g)Length of String
(cm)Distance pulled
back (cm)
# of swings in 60
seconds
Average Swings
1 14.7 50 30 68
69.2
2 14.7 50 30 70
3 14.7 50 30 71
4 14.7 50 30 69
5 14.7 50 30 68
1 49.3 50 30 72
70.4
2 49.3 50 30 70
3 49.3 50 30 69
4 49.3 50 30 71
5 49.3 50 30 70