TEAS® Science Study Guide
Reliability & Validity
These two terms sound similar but measure different things.
- Reliability — Consistency. A result is reliable if you get the same outcome each time you repeat the test.
- Validity — Accuracy. A result is valid if the experiment actually measures what it’s supposed to measure.
A result can be reliable without being valid. A scale that reads 5 pounds too high every single time is perfectly reliable — it’s consistent — but it isn’t valid, because it’s not giving the true weight.
How to strengthen each
- Improve reliability by repeating trials and using a large sample size. One measurement could be a fluke; many consistent measurements are trustworthy.
- Improve validity by controlling variables carefully and making sure the experiment truly tests the intended question.
Terms to know
- Reliability — Consistency of results when repeated.
- Validity — Whether the experiment measures what it intends to.
- Sample size — The number of subjects or trials; larger sizes give more reliable results.
What the TEAS asks most
- What does reliability mean? Getting consistent results when repeated.
- What does validity mean? Measuring what you actually intend to measure.
- How can a scientist improve reliability? Repeat trials and increase sample size.
- Can a result be reliable but not valid? Yes — consistent but inaccurate.