Final answer:
The statement that inconsistency in test instructions on different days can lead to assessment errors is true. Standardized instructions are crucial for reliable testing and avoiding experimenter bias.
Step-by-step explanation:
Indeed, a test administrator giving different sets of instructions when administering a test on different days can lead to errors in assessing the test-takers. This inconsistency can cause variability that is not due to the test taker's abilities or knowledge but rather to the testing conditions.
Standardization is a key aspect of reliable testing practices. The mean and other statistical measures used to analyze test results can only be trusted if the testing procedure, including the instructions given, is consistent across all test-takers. This ensures the validity of the comparisons made between different test-takers or different groups within a research study, such as between a control group and a test group.
Additionally, to avoid experimenter bias, standardized instructions, and procedures are crucial so that all participants have a uniform understanding of the test requirements.