the scientific method

hypothesis

an educated guess made based on an observation

principles of good experimentation

planning and design
random selection
replication
safety procedures
experimental control
large sample size
Double-blind testing

outline the steps of the scientific method that follow the design of an experiement

1. Observation
2. Hypothesis
3. Experimentation
4. Collecting and interpreting data
5. Conclusion
6. Publishing results
7. Development of Theory and Principle

limitations of the scientific method

our existing knowledge
bias
human error

importance of double-blind testing

an experiment where neither the tester nor the subject knows who gets the drug

importance of replication

to avoid bias

function of a control

to act as a comparison to the actual experiment

a theory is a supported hypothesis

true

where are the results of an investigation normally reported and published?

scientific journal

why is random selection important in experimental design?

reduces bias

what is the purpose of carrying out an experiment?

to test the hypothesis

explain the necessity for random selection

reduce bias

why is it important that scientists publish the results of their research?

• so that others can learn from successes or failures of experiments

• so others can repeat the experiment easily

how does a hypothesis differ from a theory?

hypothesis can develop into a theory

data

observations/ results

replicates

repeats / copies

experiment

test of hypothesis

theory

If a hypothesis is continuously supported by many different experiments

it proposes why something happens

law

A Theory that has shown to be valid over a long period of time

it predicts what happens

why did the scientists repeat the investigation several times before publishing their results in a scientific journal

makes it more accurate

placebo

A substance with no active medication use as a control in an experiment

Give two reasons why the method if sample selection used reduces the reliability

Biased
Only friends
Sample size too small

How could experimental design be improved?

Longer period of time
Repeat
Double-blind testing
Random selection