TY - JOUR

T1 - Trajectory analysis of discrete goal-directed pointing movements

T2 - How many trials are needed for reliable data?

AU - Blinch, Jarrod

AU - Kim, Youngdeok

AU - Chua, Romeo

N1 - Publisher Copyright:
© 2017, Psychonomic Society, Inc.

PY - 2018/10/1

Y1 - 2018/10/1

N2 - A powerful tool in motor behavior research is trajectory analysis of discrete goal-directed pointing movements. The purpose of the present analysis was to estimate the minimum number of trials per participant required to achieve the conventional level of reliability for trajectory analysis. We analyzed basic measurements of movement and three common methods of trajectory analysis within the framework of generalizability theory. Generalizability studies were used to decompose the total variance of these variables into the percent contributions from person, trial, and the person-by-trial interaction. Decision studies were then used to determine the minimum number of trials required to achieve the conventional level of reliability. The number of trials per participant needed for reliable data of discrete goal-directed pointing movements depended on the dependent variable—for example, reaction times required six or ten trials, movement times required three trials, and constant error required 47 trials. For trajectory analysis, ten or fewer trials were required for reliable dependent variables during the first half of the movement (up to peak velocity or 70% of the displacement). The number of trials required for the second half of the movement rapidly increased to 47 trials at movement termination. This increase in the number of trials required for reliable analysis of the second half of the movement was indicative of online control. Finally, correlation analysis was performed with simulated correlations on subsets of trials, and all 32 trials were required. However, 18 trials might be used without a practically significant change in the correlations.

AB - A powerful tool in motor behavior research is trajectory analysis of discrete goal-directed pointing movements. The purpose of the present analysis was to estimate the minimum number of trials per participant required to achieve the conventional level of reliability for trajectory analysis. We analyzed basic measurements of movement and three common methods of trajectory analysis within the framework of generalizability theory. Generalizability studies were used to decompose the total variance of these variables into the percent contributions from person, trial, and the person-by-trial interaction. Decision studies were then used to determine the minimum number of trials required to achieve the conventional level of reliability. The number of trials per participant needed for reliable data of discrete goal-directed pointing movements depended on the dependent variable—for example, reaction times required six or ten trials, movement times required three trials, and constant error required 47 trials. For trajectory analysis, ten or fewer trials were required for reliable dependent variables during the first half of the movement (up to peak velocity or 70% of the displacement). The number of trials required for the second half of the movement rapidly increased to 47 trials at movement termination. This increase in the number of trials required for reliable analysis of the second half of the movement was indicative of online control. Finally, correlation analysis was performed with simulated correlations on subsets of trials, and all 32 trials were required. However, 18 trials might be used without a practically significant change in the correlations.

KW - Correlation analysis

KW - Generalizability theory

KW - Kinematic landmarks

KW - Time-normalized profiles

KW - Variability analysis

UR - http://www.scopus.com/inward/record.url?scp=85037351340&partnerID=8YFLogxK

U2 - 10.3758/s13428-017-0983-6

DO - 10.3758/s13428-017-0983-6

M3 - Article

C2 - 29218584

AN - SCOPUS:85037351340

SN - 1554-351X

VL - 50

SP - 2162

EP - 2172

JO - Behavior Research Methods

JF - Behavior Research Methods

IS - 5

ER -