The validity and reliability of a new examination of the clinical competence of medical students

In a previous study we described a problem-based criterion-referenced test of the clinical competence of medical students which was felt to offer advantages over the traditional final-year examination. This paper reports the validity and reliability studies on which it is possible to judge the value of this new test when compared to the traditional approach. The results demonstrate a high level of content validity and provide evidence of the construct validity of the test. Efforts to obtain measures of concurrent and predictive validity were thwarted by a failure to attain reliable assessments of ward performance from resident and consultant staff. Satisfactory levels of internal consistency were established for the whole test. Marker reliability was satisfactory in all sections of the test except for those requiring examiners to rate practical clinical skills. This was so despite the use of simulated patients, behavioural check-lists and rater training. Possible solutions to this problem are discussed. It is concluded that this new approach overcomes many of the measurement problems inherent in the traditional final examination. It has been shown to be feasible to construct and administer in the medical school setting without the need for the allocation of additional resources.

Entrainment of breathing rate to movement frequency during work at two intensities

Ten males and six females exercised on an electrically braked cycle ergometer. Three conditions were tested: preferred pedal frequency with no cues; preferred frequency established by listening to a metronome and preferred frequency maintained by watching a digital display. Each condition was performed at a low workload and a high workload, and this set of tests was repeated once. During each test, computer sampling of pedal and breath information occurred, and the relationship of breath signal occurrences to pedal signals was plotted by a post stimulus histogram program. Fourier analysis of psh data (Time Series Spectrum Estimation) decomposed each histogram into it's frequency components. The magnitude of the frequency at the fundamental of the pedal period (F1), and it's first harmonic (F2), were assessed using F ratios. For retest results, preferred condition, 100% of subjects were entrained for both low and high workloads. With the metronome, 87% were entrained at the low workload and 94% at the high workload. For both workloads, 94% were entrained when watching a digital printout of pedal frequency. For preferred pedal rate, at the two workloads tested, the results of this study strongly support the existence of entrainment, and provide evidence for neurogenic input to ventilatory control during steady state work.

The selection and training of examiners for clinical examinations

The inconsistency of the marking in clinical examinations is a well documented problem. This project identified some of the factors responsible for this inconsistency. A standardized rating situation was devised. Five students were videotaped as they performed part of a physical examination on simulated patients. Eighteen experienced medical and surgical examiners rated their performances using an objective checklist type of rating form. No differences were evident between physicians and surgeons. The group of examiners was divided into three subgroups, one receiving no training, one limited training and one more extensive training. Examiners re-rated the same students 2 months after the first rating. Inter-rater reliability was satisfactory for the first ratings and training produced no significant improvement. A substantial improvement was achieved by identifying the most inconsistent raters and removing them from the analysis. Training was shown to be unnecessary for consistent examiners and ineffective for examiners who were less consistent. On the basis of these results, only consistent examiners were selected to take part in the interactive component of the objective structured final year examinations. The ratings in these examinations achieved high levels of inter-rater reliability. It was concluded that the combination of an objective check-list rating form, a controlled test situation and the selection of inherently consistent examiners could solve the problem of inconsistent marking in clinical examinations.

A telemetric system for the strain gauge determination of strain in bone in vivo

A method of recording bone strain in the walking animal has been described (Cochran 1969). This communication describes a method of application of train gauges directly to bone which gave dependable and reproducible results. A telemetry system designed and built for the purpose of transmitting strain patterns from the walking animal is described. This has eliminated the need for long trailing wires from the animal, and has noise free recordings which can be made from six strain gauges simultaneously. The techniques and instrument described will be used to investigate in vivo the normal deformation of bone and the effect of various internal fixation devices on this deformation.

Telemetric measurements of strain in the metacarpus of the horse: a pilot study

The advances made by the use of a telemetric system in the study of bone strain in a free-moving horse are reported. A rosette strain gauge was bonded to the craniomedial aspect of the metacarpus of the horse. Attachment of a miniature FM transmitter to lead wires facilitated telemetric transmission of of resistance changes which corresponded to limb movement. During 3 different gaits, the trace pattern remained similar, although frequency and amplitude varied. The tracings were similar to those reported in other species in which nontelemetric transmission was used.