Context  Some medical schools have recently replaced the medical school pre-admission interview (MSPI) with the multiple mini-interview (MMI), which utilises objective structured clinical examination (OSCE)-style measurement techniques. Their motivation for doing so stems from the superior reliabilities obtained with the OSCE-style measures. Other institutions, however, are hesitant to embrace the MMI format because of the time and costs involved in restructuring recruitment and admission procedures.

Objectives  To shed light on the aetiology of the MMI’s increased reliability and to explore the potential of an alternative, lower-cost interview format, this study examined the relative contributions of two facets (raters, occasions) to interview score reliability.

Methods  Institutional review board approval was obtained to conduct a study of all students who completed one or more MSPIs at a large Midwestern medical college during 2003–2007. Within this dataset, we identified 168 applicants who were interviewed twice in consecutive years and thus provided the requisite data for generalisability (G) and decision (D) studies examining these issues.

Results  Increasing the number of interview occasions contributed much more to score reliability than did increasing the number of raters.

Conclusions  Replicating a number of interviews, each with one rater, is likely to be superior to the often recommended panel interview approach and may offer a practical, low-cost method for enhancing MSPI reliability. Whether such a method will ultimately enhance MSPI validity warrants further investigation.