Dr. Ingo Larsen is testing the effectiveness of a new memory-enhancing study technique. He greets each participant at the door and escorts them into either the control group (that receives the old memory technique) or the experimental group (that receives the new memory technique). He then conducts the experiment and analyzes the results. This is all quite problematic, because of the potential presence of .

Observer - expectancy effect.

Explanation: Dr. Larsen being the observer or experimenter may subconsciously introduce a sort of cognitive bias into the experiment resulting the wrong or incorrect interpretation of the result or outcome of the experiment such that it conforms to their hypothesis. Observer-expectancy bias also called experimenter-expectancy bias can be controlled by adopting a method in which observer or experimenter is blind to the experiment's condition and thus the observer's expectation regarding the hypothesis is conained or controlled.

answer; i do believe that the correct answer is (punch card ballots);

the answer to your question is,

d. when a child was born.

-mabel < 3