1. Experimental Design Vocabulary Notes

2. Independent Variable—
factor that is changed or manipulated by the experimenter (which is me) in an experiment
referred to as the “IV”
“I” in independent stands for “I” change!

3. Levels of the IV
there are at least two levels of the IV being tested against each other
increments between levels should be ­­­­sensible, follow a pattern or norm, and always include none, zero, or absence of the IV if possible

4. Dependent Variable—
factor that responds to the changes made by the experimenter (me)
also referred to as the “DV”
ask yourself, “what depends on the IV”
ask yourself, “what is being measured or counted at the end of the experiment”

5. Hypothesis—
a prediction or educated guess about the outcome of the experiment
states the relationship between the IV and DV
describes what you think will happen without writing, “I think”

6. Hypothesis cont.— Must be written as an “If,…then” statement
EX: If the independent variable (IV) is how the IV is changed, then the dependent variable (DV) will predicted effect.
**Anything in italics and underlined above is replaced by actual variables in the experiment being tested**

7. Control— level of IV you compare results to
How does what happened to the other levels of IV compare to just one particular IV level?

8. Choosing a Control— OR…
1. IV level that is none, zero, or not changed in any way (normal)
OR…
2. IV level suggested by known standard (i.e., pH) or package directions
3. If neither of the above apply…then it’s the IV level chosen by the experimenter (me)

9. Constants—
all factors that stay the same in an experiment through every level of the IV and all repeated trials
very important so you know for sure the changes made to the IV are really what is causing the DV to respond a certain way

10. Repeated trials— the # of times an experiment is repeated
helps find an average if results constantly vary
reduces the effect of errors (i.e., maybe you measured one level of IV improperly in one trial, but not the others)

11. Title— a statement describing the experiment
indicates the relationship between IV and DV
could be written in the following format: The Effect of (changes in the IV) on the (DV)
because it is a title, all the words should be capitalized
Should not be phrased as a question

12. EDD(Experimental Design Diagram
a summary of the plan for an experiment that follows a particular format
easiest to fill in if you complete the IV and DV sections first
** Title and EDD are important but are not “key” components……if you forgot one the experiment could still be performed