Recruiting Study Participants

The decision to participate in research should be voluntary and the approach to recruitment is an important element in assuring voluntariness. In particular, how, when, why and where participants are approached and who recruits them are important elements in assuring voluntariness. Participant recruitment is intrinsically tied to informed consent and indeed, is the first step in this process. Because of this, all recruitment and advertising methods must be reviewed and approved by the Research Ethics Board (REB) prior to their implementation.

The ARISE application should fully describe the recruitment procedures and all applicable materials should be appended in the documents section. Once ethics approval has been obtained, additional approvals may still be required. Many organizations require operational approval prior to undertaking any recruitment activities with their staff, clients or in their facilities.

Participant recruitment cannot begin until REB approval has been granted.

Undue Influence

Article 3.1 of the Tri-Council Policy Statement 2 (TCPS2) states that undue influence and manipulation arise when prospective participants are recruited by individuals in a position of authority. This imbalance in power can be real or perceived. It's often seen in the workplace (employer vs employee), the health field (physician vs patient), or academics (instructor vs student), to name a few.

The REB examines the existence and acknowledgment of this relationship and what steps are in place to ensure that it has the least impact on the individual's decision to participate. The REB also considers elements of trust and dependency in relationships, such as those between caregiver and dependent. The risk of undue influence is greater in situations of ongoing or significant dependency. Pre-existing entitlements to care, education and other services should not be prejudiced by the decision of whether or not to participate in, or withdraw from, a research project.

Coercion is a more extreme form of undue influence that involves a threat of harm or punishment that would immediately negate the voluntariness of participation or otherwise.

The Use of Incentives In Research

Incentives, or "compensation," include anything offered to participants, monetary or otherwise, to encourage participation in research. This is distinct from reimbursing participants for minor incidental expenses they incur by participating in the research (for instance transportation costs or parking) which is not problematic from an ethics perspective. It should not be assumed that people must be compensated in order to participate in research studies; however, compensation can improve participation rates.

The TCPS 2 specifies that the "onus is on the researcher to justify to the REB the use of a particular model and the level of incentives." Research Ethics Boards are instructed to weigh the benefits and risks of a procedure, which means that marginal ethical considerations can be outweighed by larger benefits.

When offered, incentives should be appropriate in type and amount. That is, the incentive must not be so attractive as to be seen as an inducement to participate. The element of voluntariness must always be considered; incentives should not be so large or attractive as to encourage reckless disregard of the risks associated with participation. Researchers and REBs should be sensitive to issues such as the economic circumstances of those in the pool of prospective participants, the age and capacity of participants, the customs and practices of the community, and the magnitude and probability of harms.

Unequal Compensation

Incentives should be provided fairly to all participants, with equal compensation for equal participation being the norm; however, unequal compensation can arise in at least the following ways.


  • A study design may require a greater time commitment or more effort from some participants than others who may therefore be compensated accordingly.
  • Custom may dictate a differing level of compensation - First Nations expect compensation for Elders that differs in kind or extent from that for other participants.

Tying Compensation to Performance

Compensation may be tied to performance as a means of motivating active and energetic performance.


Participants may perform slightly different tasks (by chance, or random assignment into different experimental conditions). Although every subject has an equal expected compensation before the study begins, they do not once they are assigned to an experimental group, and sizable differences in compensation among subjects arise which are not under their control. This chance element should be explained to participants as part of the informed consent process.

Use of Lotteries

Some researchers may wish to compensate participants using a draw or lottery (defined as a chance to win a substantial prize) instead of or in addition to giving every participant a smaller prize. As there are legal issues pertaining to lotteries that must be taken into account, it is recommended that researchers refer to the Guidelines on Compensation of Human Research Participants for further details.

A lottery must not require subjects to pay money or other valuable consideration in order to participate. The probability of winning the prize should be given when recruiting participants as part of informed consent. In addition, winning the lottery must be based on skill as well as chance. Thus, many lotteries require the participants to answer a skill-testing question in order to qualify for a chance to win the prize.

Investigators must provide the odds of winning in both the information letter and within their ethics application (section 4.6 in the Research Ethics & Management Online system).