Observational studies and experiments
The method of data collection has a major influence on whether a relationship
can be interpreted as causal.
- Observational study
- There is usually the potential for a lurking
variable to underlie any observed relationship, so it is difficult to interpret
relationships.
- Experiment
- Provided the experiment has been designed well, there is little chance of lurking variables
driving the observed relationships, so any relationship will be causal.
In a badly designed experiment however, lurking variables
can still cause difficulties in interpreting relationships.