What is an effective way to reduce bias in scientific observation?

Correct answer: Record data using predetermined criteria

The direct answer is A: record data using predetermined criteria. Bias occurs when personal expectations or preferences influence what is noticed, recorded, or interpreted. Predetermined criteria reduce this influence because the observer decides in advance what counts as evidence and uses the same rule for every observation. The reasoning is: define the features and recording method before observing; apply the rule equally; record both expected and unexpected findings. Option A is correct because it promotes consistency and objectivity. Option B is wrong because recording only preferred results hides evidence and makes the record selective. Option C is wrong because unusual results may be important clues, errors to investigate, or evidence against an expectation; hiding them increases bias. Option D is wrong because copying another person’s results is not independent observation and may introduce errors or dishonesty. Clear categories, fixed time intervals, repeated observations, and written procedures can all help reduce bias. Memory cue: decide the rule before seeing the result, then record all results honestly.