Final answer:
An experiment likely to contain experimental bias is one where researchers know group assignments, potentially influencing scoring or interpretation of results, leading to experimenter bias or response bias.
Step-by-step explanation:
An experiment that would most likely contain experimental bias is one where the researchers or experimenters know which participants are in the experimental group and which are in the control group. This can lead to experimenter bias, where researchers' expectations may skew the results. In addition, when the participants know which group they belong to, it may affect their response, leading to response bias or the placebo effect. Using blind experiments or double-blind experiments where neither the participants nor the researchers know who is receiving a particular treatment can help mitigate these biases.
An example of an experiment with potential bias would be one where the people scoring tests know which children were assigned to experimental or control groups. If observers score tests of children they know are receiving a new type of educational treatment, they might unconsciously be more generous in interpreting ambiguous responses, thereby introducing bias into the experiment. To avoid such biases, neither the subjects nor the researchers should be aware of the group assignments, which is the premise of a double-blind study.
Likewise, response bias, such as in the "Bradley effect," can occur if participants modify their responses due to social desirability. Sampling biases, like conducting a student survey only during noon lunchtime hours, can also lead to incorrect conclusions about a population if not all members have an equal chance of being included in the study.