Table 1.
Analysis of overall examination performance for all 3 years
| Statistic | Y03 | Y04 | Y05 |
|---|---|---|---|
| Alpha reliabilitya | 0.81 | 0.82 | 0.79 |
| Average score | 95.14 | 144.98 | 87.94 |
| Maximum possible score | 140 | 200 | 140 |
| Standard deviation (SD) | 11.02 | 12.88 | 11.01 |
| Range of scores | 61–126 | 108–172 | 63–125 |
| Number of items | 140 | 200 | 140 |
| Average percentage correct | 68 % | 72 % | 63 % |
| Average item discrimination (Rpbis)b | 0.16 | 0.14 | 0.14 |
| Number of candidates | 262 | 278 | 273 |
aAlpha reliability ranges between 0 and 1 (i.e. no consistency to perfect internal consistency). The desirable range for high stake assessments is 0.8–0.89. The higher the stakes of the examination, the higher the value of the alpha is required to be in order to ensure a high degree of confidence in pass/fail decisions
bRpbis ranges between −1 and 1 (i.e. negatively discriminatory to perfectly discriminatory). In high stakes examinations, it is desirable to have an Rpbis approaching 0.20, as this indicates a high level of discrimination between competent and non-competent candidates