Yokely and Glenwick

What was the background context of Yokley & Glenwick (1984)?

In the 1970s–80s, psychology began testing community interventions (leaflets, phone calls, lotteries) to promote health. Vaccinations were known to be vital for preventing illness and improving outcomes, but uptake was poor. The study tested whether community interventions could raise immunisation rates in children.

What theory underpins Yokley & Glenwick (1984)?

Community interventions like prompts, letters, extended clinic access, and incentives can change behaviour and increase vaccination rates. Prior research showed such interventions increased health behaviours.

What was the aim of Yokley & Glenwick (1984)?

To evaluate the effectiveness of four different interventions in increasing preschool children's immunisation rates.

What hypothesis was proposed?

That the mailed specific prompt combined with monetary incentive would produce the greatest increase in vaccination rates, followed by increased access, specific prompt, and then general prompt.

What was the research method and design?

Field experiment with independent measures and longitudinal follow-up (2-week, 2-month, and 3-month).

What was the sample?

2101 preschool children in a US city public health centre ; 53.9 percent missing at least one vaccination ; even gender split ; 64 percent Caucasian ; mean immunisations needed 5.2.

What were the control groups?

Telephone-contact group asked about immunisations/demographics but no prompt ; Non-contact group received no intervention.

What was the General Prompt procedure?

Parents received a letter urging them to vaccinate their child, with general information but no personalisation.

What was the Specific Prompt procedure?

Parents received a letter with the child’s name, specific vaccines required, and clinic hours/locations.

What was the Increased Access procedure?

Specific prompt letter plus information on extended clinic hours and childcare offered during and after vaccination appointment.

What was the Monetary Incentive procedure?

Specific prompt letter plus details of three prize draws. Parents entered by bringing a signed slip to their appointment.

What were the key results?

Significant differences between groups ; monetary incentive group had the biggest increase ; followed by increased access ; specific prompt ; general prompt ; controls. Specific plus monetary group showed a 29 percent increase in vaccinations.

What did the cost-effectiveness analysis reveal?

Specific prompt was most cost-effective ; monetary incentive worked short-term but costly long-term ; increased access costly at first but beneficial later.

What was the conclusion?

Community interventions are effective in raising vaccination uptake. Monetary incentives had the greatest effect but other strategies also worked.

GRAVE - Generalisability?

Large diverse sample, but limited to one US city ; cultural attitudes to vaccines may differ elsewhere.

GRAVE - Reliability?

Limited because field study hard to replicate exactly ; but intervention measures were clear.

GRAVE - Applicability?

Highly applicable because governments can use interventions to raise vaccination rates, especially in pandemics.

GRAVE - Validity?

High ecological validity in real-world setting with genuine health outcomes measured.

GRAVE - Ethics?

Generally ethical ; anonymised data ; minimal deception ; small concern with incentives pressuring parents.