About Intra- and Inter- observer error in anthropometricmeasurement

[Lau Chung Sing(laurence)]

Dear BIOMCH-L,

I don't understand clearly the TEM(technical error of measurement)
and the reliability.

1. The intra-observer TEM
~~~~~~~~~~~~~~~~~~~~~~
Could you tell me the following procedure that is right or not to find
this TEM and reliability?

TEM = sqrt[(1xD1 + D2xD2 + D3xD3+...... + DNxDN) / 2N]
where D is the difference between measurements, and N is the
number of subjects.

R = 1- [(TEM x TEM) / (SD x SD)]
where SD is the total inter-subject variance.

1. 30 subjects (age 19-20) are measured.
2. Only one body dimension such as stature was measured and repeat
two times on each subject.
3. Find the differece between two repeated measure of them.
4. Then substitute the result 3 into above equation.
5. Find the reliability.

But when I calculate the SD, all the measurement values (two value each
subject) are included. Is it right?

2. The Inter-observer TEM
~~~~~~~~~~~~~~~~~~~~~~

TEM = sqrt[[sum [sum {M(n) x M(n) - sum M(n) x M(n) / K}] /N(K-1)]
Where N is the number of subjects, K is number of determinations
of the variable taken on each subject, M(n) is the nth replicate of
the measurement, where n varies from 1 to K.

1. 5 observer measure 30 subjects, one body dimension is measured
by each observer and no repeat measurement.

Is it K equals to 5 and N equals to 30 and n is 1 to 5?



Thanks in advance.

Best regards,
Laurence

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Lau Chung Sing, Laurence
UG student
Department of Industrial Engineering and Engineering Management
Hong Kong University of Science and Technology
Fax: (852)28735456
email: ie_lcsaa@stu.ust.hk
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