Figures & data
FIGURE 1 Speed-ability trade-off with effective ability as a monotonically decreasing function of effective speed
. Upper part: speed-ability curves of three persons completing a speed test (indicated by the same ability asymptote). Lower part: speed-ability curves of three persons completing an ability test (indicated by vertically displaced ability asymptotes).
FIGURE 2 Conceptual framework on the measurement of ability and speed. Individual differences in item responses and response times depend on both between-person differences in speed-ability functions (represented by speed intercept , rate
, and maximum ability
) and the speed-ability trade-off within the person (represented by effective speed
and ability
).
FIGURE 3 Resolving between-person differences in the speed-ability compromise. Upper part: Constraining effective speed provides ability estimates unconfounded by the decision on speed. Lower part: Constraining effective ability provides speed estimates unconfounded by the decision on ability (only suitable for speed tests).
