Seyyed Ali Moussavi-Najarkola AJE Vol.9 2009
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4.2.2. Intra-observer reliability test of the assessment items
Intra-observed reliability Table 12 was assessed by having the same observers participate in a test-retest procedure in which they assessed the same 31 tasks twice
in a 4–week interval. All kappa statistical analysis factors for all assessment items were 0.60 “substantial” to “almost perfect” agreement, and the test-retest
agreements were all statistically significant χ
2
test. These results indicate that agreement between assessments of the same factor by the same observer analyses
can considered “acceptable” 35.
4.2.3. Validity test of the assessment items
A validity test was conducted in a laboratory study with the same observers assessing the same set of 31 various tasks by comparing the observers’ assessment of
simulated tasks with computer–assisted 3D dimensional motion analysis utilizing the SIMI system 34,38,39,40. The same observers also participated in the field
study by comparing observers’ assessment on the same set of 31 various tasks using analysis of video-tape recordings of the tasks. Agreements were quantified between
observers’ assessment and video analysis of assessment items utilized in calculating the CEI score Table 13. In the laboratory study, for all tasks and for all assessment
items, the percentage agreements were close to or 60. In the field study, for all assessment items, the percentage agreements were 70. These agreements can be
considered “acceptable” 35, 36, 37.
Table12. Intra-observer reliability on assessment items as specified as in the CEI
25 totally observers
5 observers without any
experience 5 observers
with 2 yrs’ experience
5 observers with 4 yrs’
experience 5 observers
with 6 yrs’ experience
5 observers with 7-8 yrs’
experience Assessment
items Kappa
p Kappa p Kappa
p Kappa p Kappa
p Kappa p
Force exertion
0.71 0.008 0.61 0.003 0.65 0.022 0.73 0.002 0.74 0.037 0.79 0.025
Upper limb posture
0.81 0.031 0.73 0.001 0.77 0.011 0.80 0.001 0.83 0.001 0.89 0.001
Force frequency
0.77 0.006 0.69 0.001 0.71 0.008 0.77 0.033 0.80 0.011 0.85 0.005
Duration of force exertion
0.80 0.036 0.70 0.004 0.75 0.013 0.78 0.002 0.86 0.038 0.91 0.019
Task duration
0.83 0.017 0.76 0.013 0.79 0.004 0.83 0.001 0.86 0.001 0.90 0.008
Speed of force exertion
0.88 0.001 0.79 0.045 0.86 0.003 0.89 0.021 0.90 0.013 0.94 0.001
Parts weight 0.79 0.028 0.71 0.017 0.74 0.014 0.78 0.001 0.79 0.039 0.96 0.005 Lack of
recovery periods
0.81 0.007 0.69 0.021 0.77 0.005 0.79 0.016 0.83 0.001 0.89 0.001
Age factor 0.82 0.003 0.72 0.002 0.76 0.001 0.81 0.023 0.86 0.003 0.93 0.041
Effective items
0.86 0.045 0.80 0.015 0.82 0.020 0.85 0.032 0.90 0.041 0.93 0.033
Note: The letter p with asterisk denotes the
χ
2
significant level.
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