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

• A prediction made about a possible outcome 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

DV:

IV:IV: Trial 1Trial 1 Trial 2Trial 2 Trial 3Trial 3 Trial 4Trial 4 AverageAverage

Title: include the IV and DV

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

Conclusion1. 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!)