StATS: Withholding information (November 28, 2005)

A recent query on the IRB Forum

asked about a pilot study. The goal of the pilot study was to see if different ways of presenting the materials would lead to an improvement in the response rate among participants. The researchers wanted to withhold information about the purpose of the pilot study from the participants because it might bias their response. The writer of the query was a member of the IRB that wanted some comments about whether it is okay to withhold this information and if patients should be told if they are participating in the pilot phase of the research.

Withholding information is commonly done and accepted in research. For example, in a blinded study, you withhold information about which treatment a patient is getting until after the study is completed.

You should never withhold information about the risks of participation, of course, and the subjects need to understand the general purpose of the study. That can be easily assured here. In this particular example, I see no need to inform patients about the specific goals of the pilot study, but I do not think it would harm things to tell them that they are participating in the pilot phase of the research. Most people should understand what a pilot phase is, but you could include a general definition (a pilot study is an effort to evaluate the research methods in a small group of patients to see if there are any problems or issues that need to be resolved prior to the start of the full study) in the consent form if you like.

Note that withholding information is not quite the same thing as deception, though the line dividing the two concepts is somewhat vague. Sometimes deception about the purpose of a study is necessary to avoid bias in the research. For example, you want to find out how patients react to an environment that is constructed to produce stress. If you tell people that the purpose of the study is to look at reactions to stress, they will gird themselves up for the anticipated stress and may produce results that are not representative of their true reactions. Studies involving deception require very careful scrutiny. The guidelines of the American Psychology Association discuss this issue:

8.07 Deception in Research (a) Psychologists do not conduct a study involving deception unless they have determined that the use of deceptive techniques is justified by the study's significant prospective scientific, educational, or applied value and that effective nondeceptive alternative procedures are not feasible. (b) Psychologists do not deceive prospective participants about research that is reasonably expected to cause physical pain or severe emotional distress. (c) Psychologists explain any deception that is an integral feature of the design and conduct of an experiment to participants as early as is feasible, preferably at the conclusion of their participation, but no later than at the conclusion of the data collection, and permit participants to withdraw their data. (See also Standard 8.08, Debriefing.)

This page was written by Steve Simon while working at Children's Mercy Hospital. Although I do not hold the copyright for this material, I am reproducing it here as a service, as it is no longer available on the Children's Mercy Hospital website. Need more information? I have a page with general help resources. You can also browse for pages similar to this one at Category: Blinding in research.