Intra-observer TEM for two measurements, and inter-observer TEM involving two measurers
\[ TEM ~ = ~ \sqrt{\frac{\sum D ^ 2}{2N}} \] where
\(D ~ = ~ \text{The difference between measurements}\)
\(N ~ = ~ \text{The number of individuals measured}\)
Inter-observer TEM with more than two observers
\[ TEM ~ = ~ \sqrt{\sum\nolimits_1 ^ N \left (\sum\nolimits_1 ^ K M ^ 2 ~ - ~ \frac{\left (\sum\nolimits_1 ^ K M \right ) ^ 2 / K}{N(K ~ - ~ 1)} \right )} \] where
\(N ~ = ~ \text{Number of subjects}\)
\(K ~ = ~ \text{Number of observers}\)
\(M ~ = ~ \text{Measurement}\)
Total TEM for two observers and two measurements per observer
\[ \text{Total TEM} ~ = ~ \sqrt{\frac{TEM ~ \times ~ (intra_1) ^ 2 ~ + ~ TEM ~ \times ~ (intra_2) ^ 2}{2} ~ + ~ TEM \times (inter) ^ 2} \]