What is the difference between a scientific hypothesis and a prediction?
Quick answer
A scientific hypothesis is a testable explanation for an observation. A prediction is an expected result derived from that explanation, often written as “If … then …” [S1] In short, the hypothesis proposes an explanation; the prediction states what you would expect to observe if that explanation were correct. They are connected, but they do different jobs.
The question, the details, the next step.
I keep mixing these up. What’s the simplest way to tell a hypothesis from a prediction?
Ask two different questions:
- Hypothesis: What explanation could account for the observation?
- Prediction: What result would I expect if that explanation were correct?
A hypothesis is a suggested, testable explanation. A prediction states an expected result based on a selected hypothesis, often in an “if … then …” form. [S1] So the hypothesis proposes an explanation; the prediction describes an expected observation that follows from it. To check your wording, see whether the two sentences answer different questions.
Could you show that with a biology example, without turning it into instructions for an experiment?
Suppose the observation is: Some seedlings beneath a dense tree canopy have fewer leaves than nearby seedlings in an open area. This is a made-up example for practicing the distinction, not a report about a particular study.
A possible hypothesis is: Lower light beneath the canopy limits leaf production. This offers an explanation for the observed difference.
A prediction that follows from it could be: If lower light limits leaf production, then seedlings in the lower-light setting would be expected to have fewer leaves than seedlings in the more open setting. The prediction states an expected pattern; it does not claim that the pattern has been observed or establish that the explanation is correct.
Notice that the prediction uses the same idea as the hypothesis, but it has a different job: it says what you would expect to observe if the proposed explanation were right.
How do I make sure my prediction isn’t just a reworded hypothesis?
Check whether each sentence does its own job. The hypothesis offers an explanation. The prediction names an expected observation that follows from that explanation.
For the seedling example:
- Hypothesis: “Lower light beneath the canopy limits leaf production.”
- Prediction: “If lower light limits leaf production, then seedlings in the lower-light setting would be expected to have fewer leaves than seedlings in the more open setting.”
The first proposes why there may be a difference. The second says what pattern you would look for if that explanation were correct. If your prediction only repeats the proposed cause, revise it to state an observable result. The “if … then …” frame can help make the link clear. [S1]
Can you give me a reusable sentence frame for my own research question?
Start with the observation, then write one explanation and one expected result:
Observation: “I notice that [specific pattern or event].”
Hypothesis: “A possible explanation is that [proposed reason] contributes to [pattern].”
Prediction: “If [proposed reason] is correct, then I would expect to observe [specific result] in [relevant setting or comparison].”
For a biology question, the result might describe a visible pattern such as a difference in leaf number. Keep the prediction focused on what would be observed, rather than stating the explanation again. These frames help separate an explanation from the expected result; they do not establish that the proposed explanation is true.
A practical checklist
Write the observation as a pattern or event, without presenting its cause as settled.
State a possible, testable explanation in the hypothesis.
Use “If … then …” to connect the explanation to an expected result.
Name an observable result that could match the prediction.
Check that the prediction states an expected observation rather than repeating the explanation.
A few more useful answers
Can a prediction be written without “if … then …”?
Yes. The important distinction is that a prediction states an expected result based on a selected hypothesis. “If … then …” is one useful way to show that link. [S1]
What is the quickest way to identify each part?
Ask whether the sentence offers an explanation for an observation or states an expected result that follows from an explanation. The first is the hypothesis; the second is the prediction. [S1]
Sources
References used for this guide.
- [S1] OpenStax Concepts of Biology: The Process of Science openstax.org · Checked