We employed a randomized study of 344 subjects to determine whether an initial contact letter accompanied by an informational newsletter increased participation in a population-based case-control study. The results indicated that there was no benefit in including a newsletter with a letter of introduction. There may have been a slight detrimental effect, since those who received the newsletter were less likely to consent to an in-person interview (82%) than those who did not (88%).
No takes yet. Share an insight, caveat, or question.
Heuser et al. (1991) studied this question.
Synapse has enriched 5 related papers. Consider them for comparative context: