# Experimental Design

Experimental Design
Student Cheat Sheet 2015
Variables
• Independent variable (IV): the
variable that is purposely changed in
an experiment.
• Dependent variable (DV): the
variable that responds to the change
(IV). It is measured or observed.
IV groups
• Different types of IVs that are used
– Ex. Type of Vitamin
• IV Groups: Vitamin K, Vitamin A, Vitamin C
Always include UNITS on IV or DV if needed
Constants
• Things that are kept the same in an
experiment. Everything besides the IV
must be kept constant for the
experiment to be valid.
• It’s important to keep all other variables
constant so the experimenter knows what is
causing the DV to change.
Control
• The group that is used as a standard
of comparison in an experiment. The
control may be “no treatment” or
“experimenter selected” It allows
you to know if the IV truly affected
the DV.
Experimental Question
• A question which deals with how the
IV will affect the DV.
• How does the ____________(IV)
affect the ______________ (DV)?
• Don’t forget the Question Mark!
Hypothesis
of an experiment
• It must be testable and based on previous
knowledge
• It is a statement that includes the IV and DV.
• Must include: If … then
• Must be specific! (Pick an IV group and DV
change)
Data Table
• Must have TITLE at the top including the IV
and DV: The effect of __________ (IV) on the
____________ (DV).
• IV: left column- include units
• DV: top middle- include units
• Trials- top
• Average- right column
Title: include the IV and DV
DV:
IV:
Trial 1
Trial 2
Trial 3
Trial 4
Average
Graphs
• Must have title at the top- the same as the title on
data table
• X-axis- IV (units)
• Y-axis- DV (units)
• Half Rule- Use most of the graph paper
• Graph only the Averages!
• Include labels or keys for multiple lines or bars
• Use appropriate scale on each axis
Bar graph or line graph?
• Line graph: data is related and
continuous ex. Time or Temperature
• Bar graph: data is unrelated
categories or discontinuous ex.
Honda, Ford, Chevy
Conclusion
1. Purpose of the lab- restate the experimental
question
2. Data- report major findings- put data table
into words using averages
3. Hypothesis – state it and tell if it was
“supported” or “not supported” by the data
4. Patterns in the data (look at graph)
5. Recommendations for improvements
(Players Don’t Hate Players Rock!)