Table 2.

Variance components of MMI scores for partially crossed naturalistic data from a national assessment centre for selection into GP specialty training

Component and their interaction	Explanation of interactions	Variance component estimate	Proportion of total variance from each factor (%)	Effect sample (degrees of freedom-df)
Candidate	The consistent differences between candidates’ ability across interviewers and MMI stations	0.47	28%	1381
MMI question	The consistent differences in MMI station difficulty across candidates and interviewers	0.02	1%	5
Interviewer	The consistent differences in interviewer stringency across candidates and interviewers	0.15	9%	241
Interviewer with MMI question	The varying question-specific stringency of interviewers between MMI questions across candidates	0.06	3%	693
Candidate with MMI question	The varying MMI question-specific difficulty between candidates across interviewers	0.30	18%	6905
Candidate with interviewer	The varying views that interviewers have of candidates because of their differing perspectives	0.67	40%	6905