Summary
The independent variable is changed, the dependent variable is measured and controlled variables are kept constant.
In depth
The independent variable (IV) is manipulated, the dependent variable (DV) is measured, control (controlled) variables are kept constant. Confounding variables can distort results. Operational definitions say how to measure.
Only one variable should change at a time. Uncontrolled variables reduce validity; randomisation spreads them evenly. Dependent variables need precise measurement.
Example: when testing light intensity effects on photosynthesis, keep temperature and CO2 constant.
Frequently asked questions
What is Variables?
The independent variable is changed, the dependent variable is measured and controlled variables are kept constant.
Which area of biology covers Variables, and how advanced is it?
Variables 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 Experimental Design, Reliability and Validity, Colorimetry.
Can you give an example of Variables?
In an enzyme experiment, temperature is the IV, rate is the DV, and pH and enzyme concentration are controlled.
What should I learn before Variables?
Variables 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, Control Group.
What topics are related to Variables?
The closest topics to Variables are Experimental Design, Reliability and Validity, Colorimetry, Hypothesis. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Variables?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Variables. To practise the whole of Lab Methods & Biostatistics, use the Lab Methods & Biostatistics quiz.
How is Variables different from Experimental Design?
Variables: The independent variable is changed, the dependent variable is measured and controlled variables are kept constant. Experimental Design: Randomisation, replication, blocking and blinding reduce bias and confounding. Read both side by side and note what each one explains.
How should I study Variables 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 Experimental Design and explain the difference aloud. Finally, take the Lab Methods & Biostatistics quiz and come back to this page for any question you miss.