Summary
Reliable results are repeatable; valid results measure what they claim to measure.
In depth
Reliability: repeatability and precision (repeat measurements, large samples). Validity: measures the intended variable, controls are in place. Accuracy: closeness to true value.
Repeats show reliability; controls ensure validity. Systematic errors reduce accuracy; random errors reduce precision.
Key idea: precise measurements can still be wrong if there is bias.
Reliability means that repeated measurements or experiments give consistent results (precision); it is improved with replicates, careful technique and calibrated instruments. Validity means the experiment actually measures what it claims to measure and the conclusion follows from the data.
Accuracy is closeness to the true value. A result can be reliable but not valid, such as a scale that consistently reads 2 kg too much. Validity is threatened by uncontrolled variables, bias and poor design. Replication within an experiment and repetition by others are both important.
Example: counting only one leaf per plant may be reliable but not valid for estimating total leaf area.
Remember: precise is not the same as accurate.
Frequently asked questions
What is Reliability and Validity?
Reliable results are repeatable; valid results measure what they claim to measure.
Which area of biology covers Reliability and Validity, and how advanced is it?
Reliability and Validity is one of the 51 topics in Lab Methods & Biostatistics. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Variables, Scientific Method, Reproducibility in Science.
Can you give an example of Reliability and Validity?
A thermometer that is consistent but miscalibrated is reliable but not accurate.
What should I learn before Reliability and Validity?
Reliability and Validity is a Beginner topic, so no earlier topic is required. Other Beginner topics in Lab Methods & Biostatistics that pair well with it include Scientific Method, Hypothesis, Variables.
What topics are related to Reliability and Validity?
The closest topics to Reliability and Validity are Variables, Scientific Method, Reproducibility in Science, ANOVA. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Reliability and Validity?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Reliability and Validity. To practise the whole of Lab Methods & Biostatistics, use the Lab Methods & Biostatistics quiz.
How is Reliability and Validity different from Variables?
Reliability and Validity: Reliable results are repeatable; valid results measure what they claim to measure. Variables: The independent variable is changed, the dependent variable is measured and controlled variables are kept constant. Read both side by side and note what each one explains.
How should I study Reliability and Validity step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Variables and explain the difference aloud. Finally, take the Lab Methods & Biostatistics quiz and come back to this page for any question you miss.