Every study starts with a question, which researchers turn into a hypothesis — a prediction about what they expect to find.
A vague idea must become a hypothesis specific enough to be testable.
A scientific hypothesis must be falsifiable: there must be possible evidence that could show it is wrong (e.g., finding that most teens feel calmer with social media would disprove the idea that it makes them more anxious).
Operational definitions spell out exactly how each variable will be measured, such as phone screen-time data for social media use and a standardized questionnaire for anxiety.
Clearly defined variables let other researchers repeat the same procedure, which makes replication possible.
Key terms
hypothesis
A testable prediction about what researchers expect to find.
falsifiable
Able to be shown incorrect; there must be possible evidence that could prove the hypothesis wrong.
operational definition
A clear definition of exactly how a variable will be measured.
replication
Repeating a study to see whether similar results are found.