Experimental Design

Question 1

Independent (predictor or explanatory) variable

Answer 1

The cause
Variable that is controlled or changed in the experiment

Question 2

Dependent (outcome or response) variable

Answer 2

The effect
Variable being tested and measured

Question 3

Hypothesis

Answer 3

tentative answer to a well-framed question

Question 4

Experimental Group

Answer 4

The group that receives the treatment in an experiment

Question 5

Control Group

Answer 5

Identical to experimental treatments except for one independent variable
Provides a baseline that lets us see if the treatment has an effect

Question 6

Experimental unit

Answer 6

Physical entity to which a treatment is randomly applied and on which an observation is made

Question 7

Internal Validity

Answer 7

Extent to which you can be confident that a cause and effect relationship established in a study cannot be explained by other factors
Control groups help ensure the internal validity of the experiment

Question 8

Confounding variable

Answer 8

Unmeasured variable that effects both the cause and effect

Question 9

Sample size

Answer 9

The number of experimental units per group

Question 10

Negative Control Group

Answer 10

Experiment group treated the same as all the other but not expected to change from any variable

Question 11

5 keys steps in designing an experiment

Answer 11

Consider your variables and how they are related
Write a specific, testable hypothesis
Design experimental treatments to manipulate your independent variable
Plan how you will measure your dependent variable
Randomly assign subjects to groups (control and experimental)

Question 12

Explain the difference between Independent and Dependent Variable

Answer 12

Independent can be changed
Dependent is the effect/response

Question 13

Explain the difference between Control and Experimental Group

Answer 13

Experimental group - gets the treatment
Control group - provides a baseline for the experiment, and expected result

Question 14

Explain the purpose of including a suitable control group in an experiment

Answer 14

Creates a baseline for the experiment, lets us know is our independent variable has an effect on the dependent variable

Question 15

Explain the purpose of standardizing variables in an experiment

Answer 15

Determines if the response was caused by just the independent variables and not other factors (confounding variables)

Question 16

Explain the purpose of increasing sample size within an experiment, as well as repeating experiments

Answer 16

Makes it less likely that we reach a wrong conclusion