The scientific method

Hypothesis, variables, control group, randomisation and bias: building a protocol that proves something.

The outline, topic by topic

Each topic is weighted the way the exam weighs it.

Hypothesis: what is it?
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A provisional, testable answer to a research question.
The data must be able to refute it.
The scientific method: which step comes after "Ask a question"?
- Review the literature
- State a hypothesis
- Design the protocol
- Collect the data
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Review the literature
Each step builds on the one before: the literature shows what is already known and grounds the hypothesis, the hypothesis dictates the protocol, and one concludes only after analysing the data.
Independent variable: what is it?
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The factor the researcher varies or whose effect is studied.
Example: the type of warm-up.
A coach tests a new warm-up on his best athletes and compares with the others. What is wrong?
- Attrition bias: some athletes dropped out of the study
- Publication bias: only the good result will be published
- Selection bias: the groups were not comparable
- Confirmation bias in the athletes
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Selection bias: the groups were not comparable
The best athletes already differ from the others: a gap would come as much from their level as from the warm-up. The athletes should have been assigned at random.
Dependent variable: what is it?
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The measure expected to change under the independent variable.
Example: jump height.