Statistical indices of predictiveness of overestimation of current ability on a set of bimanual and bipedal tasks for consistent bimanual and bipedal overestimation
| Tasks | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | Accuracy (%) | Discriminability (d′) | |
|---|---|---|---|---|---|---|---|
| Sensitivity (of Q to O): the proportion of consistent overestimators (O+) who overestimate task Q, that is, P(Q+|O+). Another name for this is the hit rate or true positive rate. | |||||||
| Specificity (of Q for O): the proportion of patients that are not consistent overestimators who do not overestimate on Q, P(Q−|O−). It is equal to 1 minus the false alarm rate of Q, that is, P(Q+|O−). Another name for specificity is the true negative rate. | |||||||
| PPV: the positive predictive value of Q for O. This is the proportion of patients that overestimate task Q who would be correctly identified as O+ on the basis of observing Q+, that is, P(O+|Q+). | |||||||
| NPV: the negative predictive value of Q for O. This is the proportion of patients that do not overestimate task Q who are not consistent overestimators, that is, P(O−|Q−). | |||||||
| Accuracy: the predictive accuracy of Q for O. This is the proportion of patients for which the outcome of Q matches the state of O, that is, the proportion that are correctly classified by Q with respect to O. | |||||||
| Discriminability: D-prime (d′), the classical signal detection theory index of detectability. It estimates how far the O− and O+ patients are separated on the basis of Q− and Q+. | |||||||
| Prevalence: the proportion of patients who are consistent overestimators, that is, P(O+). | |||||||
| Consistent bimanual overestimation (prevalence 52.4%) as predicted by: | Tie a knot? | 95.5 | 85.0 | 87.5 | 94.4 | 90.5 | 2.49 |
| Clap hands? | 77.3 | 90.0 | 89.5 | 78.3 | 83.3 | 1.89 | |
| Shuffle cards? | 66.7 | 100 | 100 | 73.1 | 82.5 | 2.42 | |
| Row a boat? | 95.0 | 95.0 | 95.0 | 95.0 | 95.0 | 2.93 | |
| Catch a ball? | 100 | 40.0 | 64.7 | 100 | 71.4 | 1.96 | |
| Wash hands? | 100 | 55.0 | 71.0 | 100 | 78.6 | 2.27 | |
| Unscrew bottle? | 81.8 | 90.0 | 90.0 | 81.8 | 85.7 | 2.04 | |
| Cut bread? | 90.9 | 60.0 | 71.4 | 85.7 | 76.2 | 1.51 | |
| Consistent bipedal overestimation (prevalence 11.9%) as predicted by: | Ride a bicycle? | 60.0 | 70.3 | 21.4 | 92.9 | 69.0 | 0.64 |
| Climb a ladder? | 80.0 | 89.2 | 50.0 | 97.1 | 88.1 | 1.72 | |
| Jump? | 80.0 | 91.9 | 57.1 | 97.1 | 90.5 | 1.89 | |
| Walk? | 80.0 | 70.3 | 26.7 | 96.3 | 71.4 | 1.03 | |