A controlled experiment is one that a. proceeds slowly enough that a scientist can make careful records of the results. b. tests experimental and control groups in parallel. c. is repeated many times to make sure the results are accurate. d. keeps all variables constant.

Verified step by step guidance

1. Understand the concept of a controlled experiment: A controlled experiment is designed to test the effects of one variable at a time by comparing a test group with a control group.
2. Identify the role of control groups: Control groups are used as a baseline to compare the results of the test group that receives the experimental treatment.
3. Analyze the options: Option (b) mentions testing experimental and control groups in parallel, which aligns with the definition of a controlled experiment.
4. Eliminate other options: Options (a), (c), and (d) do not specifically address the simultaneous comparison of experimental and control groups, which is essential for a controlled experiment.

Key Concepts

Controlled Experiment

A controlled experiment is a scientific test where one variable is changed while all other variables are kept constant. This allows researchers to isolate the effects of the independent variable on the dependent variable, ensuring that any observed changes can be attributed directly to the manipulation of the independent variable.

Variables

In experiments, variables are elements that can change or be controlled. The independent variable is what the experimenter manipulates, while the dependent variable is what is measured. Control variables are kept constant to prevent them from influencing the outcome, ensuring the validity of the experiment.

Replication

Replication refers to the process of repeating an experiment multiple times to verify results. This is crucial for establishing the reliability and accuracy of findings, as consistent results across multiple trials strengthen the evidence for a hypothesis and reduce the likelihood of random error.