3. Experimental Design Flashcards
What are Experiments?
Experiments are used to study cause and effect relationships
What is the Independent Variable?
The cause (X)
The variable that is controlled or changed in an experiment
AKA Explanatory or Predictor variable
What is the Dependent Variable?
The effect (Y)
The variable being tested and measured in an experiment
AKA Response or Outcome variable
What is Experimental Design?
Experimental design means creating a set of procedures to systematically test a hypothesis
What is a Hypothesis?
A hypothesis is a testable and predictive statement that proposes an explanation or relationship between variables,
What are the 5 Key Steps in Designing an Experiment?
- 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)
What is the Experimental Group?
the group(s) that receives the treatment in an experiment
(also known as test treatment)
What is the Control Group?
Identical to experimental treatments except for ONE independent variable feature (the control group provides a baseline that lets us see if the treatment has an effect)
What is Internal Validity?
Internal validity is the extent to which you can be confident that a cause-and-effect relationship established in a study cannot be explained by other factors
What is the Experimental Unit?
The experimental unit is the physical entity to which a treatment is randomly applied, and on which an observation is made
What are Standardized Variables?
variables that you need to keep equal/same in all your treatment groups
A total of 200 students have agreed to participate in a study comparing the effects of caffeinated cola and caffeine-free cola on heart rates.
Answer the following questions:
* Write a suitable hypothesis for this experiment.
- In your hypothesis, identify the independent
and dependent variable.
Hypothesis:
If people consume more caffeinated cola, then they are likely to have higher rates compared to people who consume caffeine-free cola
Independent Variable:
Levels of Caffeine in Cola
Dependent Variable:
Heart Rate
A total of 200 students have agreed to participate in a study comparing the effects of caffeinated cola and caffeine-free cola on heart rates.
Answer the following questions:
* Which group in the study would represent the control group?
- Which group in the study would represent the experimental group?
The Control Group provides a baseline to see if the treatment has an effect
The Control Group would be the group receiving caffeine-free cola.
The Experimental Group would be the group receiving the caffeinated cola.
A total of 200 students have agreed to participate in a study comparing the effects of caffeinated cola and caffeine-free cola on heart rates.
Answer the following questions:
* What is the experimental unit in this study?
- List four examples of standardizing variables in this study
The Experimental Unit is the Student
Standardized Variables:
- Age
- Sex
- Health Status
- Volume of Cola Consumed
- When Cola is Consumed
- Amount of Caffeine in Cola
- Method of Measuring Heart Rate
