Experimental Design - Key Terms

the variable the experimenter measures

• Independent

• Dependent

• Controlled

• Control

the variables that are kept the same in order to test the relationships between the independent and dependent variables

• Independent

• Dependent

• Controlled

• Control

the variable for which quantities are manipulated (selected or changed) by the experimenter

• Independent

• Dependent

• Controlled

• Control

how close the experimental result obtained is to the accepted, or ‘true’, value of the particular quantity subject to measurement

• Accuracy

• Precision

• Reliability

• Repeatability

the test that ensures the results are due to the independent variable and not other factors

• Validity

• Control

• Controlled variable

• Random

how closely two or more measurements agree with other.

• Accuracy

• Raliability

• Precision

• Repeatability

used an incorrect quantity of a chemical, timed an experiment inconsistently, or not followed the method carefully enough.

• Random error

• Systematic error

• Accuracy

• Mistake

Affects the accuracy of a measurement and causes reading to differ from the true value by a consistent amount each time resulting in a measurement is too high or too low. Often due to equipment issues such as poorly calibrated equipment.

• Random error

• Systematic error

• Mistake

• Validity

affect the precision of a measurement and are present in all measurements except for measurements involving counting. Can be reduced by obtaining more or repeated measurements, calculating a mean or refining the method.

• Random error

• Systematic error

• Mistake

• Validity

the closeness of agreement between independent results obtained with the same method on identical test material, under the same condition

• Reliability

• Repeatability

• Reproducibility

• Validity