A control sample in an experiment serves as a baseline for comparison against the experimental group, which is exposed to the variable being tested. A standard is a known benchmark used for calibration or comparison in measurements.
The difference between a control sample and a standard in experimental design is fundamental for proper scientific evaluation. A control is used in an experiment to provide a baseline against which the effect of a tested variable can be measured. For instance, in a biology experiment studying plant growth, a control group of plants would be kept under normal conditions while the experimental group might receive a new type of fertilizer (the independent variable).
A standard, on the other hand, generally refers to known quantities or benchmarks used for comparison, for example, a sample with a known concentration of a substance to calibrate measurements. It is crucial in experiments to ensure that control groups and experimental groups are identical except for the presence or absence of the experimental manipulation. This ensures that any observed differences are due to the variable being tested, thereby leading to reliable and valid results.