Persuasion in Medicine: Experimental Evidence on Sender and Signal Effects

The aim of our study is to identify what sender/signal combinations are most persuasive in encouraging low socioeconomic males living in the U.S. to take-up seasonal flu vaccination. We plan to recruit male subjects and randomly assign them to three persuasion treatments: two of which vary dimensions of the sender of medical recommendation (concordance and authority treatments) and one which varies the signal (validation). Specifically, we will show subjects videos of either black or white male "actors" providing scripted information on the flu vaccination. We will cross-randomize race with authority as the actor will portray either an actor or a layperson. In addition, we will vary the script used in the experiment between one that acknowledges past injustices and one that does not. Lastly, we will randomize offer prices for a free flu shot coupon. The design requires collection of baseline and endline surveys combined with administrative data from pharmacies about coupon redemption. The outcomes of interest are posterior beliefs about seasonal flu vaccination, demand and WTP for a free flu shot coupon and redemption of the coupon.

2019-10-31

2020-02-29

Our primary outcomes of interest are prior/posterior beliefs about the risk/benefits of the flu shot, perceptions of the sender, willingness-to-pay (WTP) for a free flu shot coupon, level of attention and recall from the infomercial video, and redemption of said coupon.

We will recruit approximately 5,100 African American or Caucasian adult males with a high-school diploma or less. We will oversample African American individuals, emphasizing low-income and minority men because these characteristics are correlated with lower relative take-up of flu vaccination. After informed consent is obtained, subjects will be asked about sociodemographic information (age, education, income and marital status), healthcare experience and past medical history, knowledge and beliefs about flu vaccination, and location of the nearest pharmacy. We will then randomly assign the adult male subjects to videos which contain one of black or white actors playing the role of either a doctor or a layperson as well as different scripts. The content of the infomercial will be the safety and effectiveness of adult seasonal flu vaccination. After the video, we will obtain information on beliefs regarding flu vaccination, feedback on the video, attention to the video and willingness-to-pay for a flu shot coupon. We will track coupon redemption, which is redeemable at most pharmacies nationwide.

We will use computer randomization via Facebook.

The unit of randomization is the individual.

No

Not applicable - though we may need to correct for correlation in the error term across actor-script-types.

Approximately 5,100 men (3,444 African American men and 1,656 Caucasian men) will be recruited.

Approximately 5,100 men will be recruited. Each subject will be randomly assigned to either concordance or discordance group with 50/50 chance. For African American subjects assigned to a concordant actor, the subjects will then be assigned to either a doctor or layperson with a 50% chance. For African American subjects assigned to a discordant actor, all subjects will be assigned to a doctor actor but will be randomly assigned to either a validation message or normal message with a 50% chance. All Caucasian subjects will be assigned to a doctor actor delivering a normal message.

We need a sample size of 5,100 (3,444 black and 1,656 white respondents) to test our main hypotheses with 80% power and at a significance level of 0.05. Using a sample size of 5,100 we can detect a difference in means (in standard deviation units) of (1) 0.08 between concordance and discordance group for both races; (2) 0.12 between concordance and discordance group within black respondents assigned to an authority figure; (3) 0.14 between concordance and discordance group within white respondents assigned to an authority figure; and (4) 0.14 between validation (M2) and normal message (M1) group within black respondents assigned to a discordant authority figure.

Pre-analysis plan for Persuasion in Medicine