1. 1.1.3 Experimentation

2. 1.1.3 Experimentation Syllabus requirements
A full understanding of the principle of experimentation to include
Careful planning and design
Safety of procedure
Necessity and selection of an experimental control
Explaining why sample size is important
Explaining why random selection is important
Explaining why replicates are important
Explaining why double - blind testing is important

3. Principles of experimentation
This is not a fair test because…

4. This is not a fair test because:
They will run on different surfaces
They are wearing different shoes
They are wearing different clothes
One is carrying a bag
Etc.

5. How to organise an experiment OR The Principles of Experimentation
Plan and design the experiment
Be aware of Safety procedures
Select organisms at random
Use a large enough sample size
Use a control group
Use Double-blind testing
Change one factor at a time
Measure changes
Analyze the results
State possible sources of error
Repeat the experiment

6. What is an experiment?
1. An experiment is a controlled test.
2. Only one variable should be changed at a time.
a. Independent variable – changed by the experimenter.
(Hint: I change the Independent variable)
b. Dependent variable (Responding) – the effect.

7. What is an experiment?
3. Constants do not change. 4. Controlled variables are those which could change, but are not allowed to. 5. Two parts to an experiment: a. Control group – normal conditions. b. Experimental group(s) – variables are changed. 6. Prediction is the goal of experiments.

8. What is double-blind testing?
During trials to examine the effectiveness of a new pill, two sample groups are taken.
One group gets the pill under test and the other a placebo. All pills are the same size, colour, taste, etc., but coded differently.
When the trials are over, it is possible to distinguish between the control and experimental groups. This ‘double-blind’ testing method avoids bias during the trials.

9. Learning check
QUESTION: What is an experiment? ANSWER: It is a controlled test where only one variable is changed at a time.

10. An example of an experiment
Observation: It has been suggested that large daily doses of Vitamin C protect against the common cold virus.
Hypothesis: Vitamin C protects against the common cold virus

11. An example of an experiment
Experiment design: Ten adult males in their mid twenties who are friends of the investigator were chosen to test the possible value of vitamin C. 5 of them were given 3000mg of vitamin C a day; the other 5 were given a placebo. Which is the control group? Which is the experimental group? Is this a good experiment?

12. Problems with experiment design
All males All mid twenties All friends Not a large enough sample

13. A Good Experiment Should Have only one variable
Use a large number of samples
Use random selection
Be repeated
Use double blind testing

14. Revision Questions
Experimentation

15. A hypothesis confirmed by experiment
Fill in the table
Key Word
Explanation
Variable
A hypothesis confirmed by experiment
Scientific Method
Control
An “educated guess”

16. Completed table Key Word Explanation Variable
Any condition which changes during the experiment
Theory
A hypothesis confirmed by experiment
Scientific Method
A process of investigation
Control
A comparison
Hypothesis
An “educated guess”

17. QUESTION: Explain Independent variable
The variable that is changed by the person doing the experiment.
Remember: If I am doing the experiment then I change the Independent variable

18. QUESTION: Explain Dependent variable
This is what changes in response to the changing of the independent variable.

19. QUESTION: What is a control or control group?
Experiment(s) that are subjected to normal conditions.
You usually know how these are going to react.

20. Learning objectives
Can you state about eight principles of experimentation?
5. Random Selection
6. Replication
7. Double-Blind Testing
8. Sources of errors
Planning & Design
Safety Procedure
Control Experiment
Sample Size

21. How would you organise an experiment?
Plan and design the experiment
Be aware of Safety procedures
Select organisms at random
Use a large enough sample size
Use a control group
Use Double-blind testing
Change one factor at a time
Measure changes
Analyze the results
State possible sources of error
Repeat the experiment

22. END