At BIT, we are constantly on the look-out for interventions that can scale dramatically at low or even no cost. That’s why we’re excited that some of our evidence-based interventions will hit millions of letter boxes across England, Scotland and Wales this summer.
The Household Enquiry Form (HEF) plays a key role in keeping the electoral register up-to-date. Each year, local authorities send this form to all households in their area to confirm who lives there; any resident who is eligible to vote but not already registered will subsequently be invited to register.
About half of all households don’t complete the form the first time it’s sent. Electoral officers have a duty to ensure that their electoral register contains all eligible voters, and non-response can have a significant impact on the register – not to mention individuals’ ability to vote. Recent studies have shown that there remain gaps in the register’s completeness, particularly among younger people, non-homeowners, certain ethnic minorities, and EU and Commonwealth citizens.
To overcome this issue, local authorities are required by law to send reminders and canvass door to door, visiting households that have not responded and encouraging them to provide the required answers. This is resource-intensive: some authorities regularly spend six-figure sums each year chasing those who don’t respond.
With funding and support from the Electoral Commission, we designed a randomised controlled trial (RCT) with the goal of increasing initial HEF response rates and saving local authority resources. Local authorities can’t change the form itself, but they have the freedom to change the cover letter and envelope that it’s sent in. Our trial took advantage of this freedom to test different messaging strategies.
Business-as-usual envelope and cover letter in Hull
We received dozens of expressions of interest from local authorities interested in improving their HEF response rates. We wanted to test our interventions in challenging yet different environments, so after careful review, we selected Hackney Council and Hull City Council to partner with.
Hackney and Hull are different in many ways – Hull residents are older, predominantly white, and more likely to own a home, whereas Hackney residents are younger, more ethnically diverse, and more likely to rent. However, both councils have low historic HEF response rates.
Our letters reached virtually every household in these local authorities – this provided us with a very large sample size (N > 225,000) and allowed us to test 9 interventions against the business-as-usual HEF communications.
What we found in our trial surprised us: our most effective intervention was the business-as-usual letter repackaged in a modified envelope.
In Hull, the modified envelope was brown, featured the local authority logo on the front, removed all “Your Vote Matters” campaign content, and included a specific note on the front that made it clear that whoever lived at that address needed to respond.
Promisingly, exploratory subgroup analysis suggests that the modified envelope tested in Hull was particularly effective for harder-to-reach households. Of households that did not return the HEF initially in the previous year, initial HEF response rates were 25% higher for those that received the Envelope compared to the business-as-usual HEF materials.
If scaled in a local authority with 100,000 properties, we estimate that the modified envelope would generate an additional 3,400 initial HEF responses and save £5,000 in reminder and canvassing expenses.
Modified envelope (Hull)
Some of our other interventions produced modest but statistically significant increases in initial responses (e.g. Costs and Hassle), while others (e.g. Easy and Call to Action) produced significant increases in electronic responses, which are easier and less costly for local authorities to process.
The Electoral Commission has already shared these results with local authorities across Great Britain and encouraged them to adopt our trial’s most promising interventions. As many local authorities will begin their annual canvass soon (if they haven’t already), we have a special message for our British followers — keep an eye on your letter box for signs of the scale-up, and of course, make sure you respond!
