1. 1.1.3 Experimentation

2. Can you state about eight principles of experimentation?
Learning objectives
Can you state about eight principles of experimentation?
Random Selection
Replicaton
Double-Blind Testing
Sources of errors
Planning & Design
Safety Procedure
Control Experiment
Sample Size

3. 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.

4. 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.

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

7. 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

8. 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?

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

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

11. Learning objectives Random Selection Planning & Design Replicaton
Can you state about eight principles of experimentation?
Random Selection
Replicaton
Double-Blind Testing
Sources of errors
Planning & Design
Safety Procedure
Control Experiment
Sample Size

12. END