Satterthwaite degrees of freedom [Regulatives / Guidelines]

posted by Helmut Homepage – Vienna, Austria, 2008-03-06 14:57 (6297 d 09:11 ago) – Posting: # 1663
Views: 15,993

Dear SKR!

❝ My question is can we manually calculate MIXED ANOVA results?


Theoretically yes, practically no.
The solution of a linear mixed effect model (this is not an ANOVA!) is based on a numeric iterative procedure – so if you have truly a lot of spare time, you should be able to do it… :lol3:

❝ One more thing is, what DDFM=SATTERTH; indicates?


DDFM: D (?) Degrees of Freedom
SATTERTH: Welch-Satterthwaite approximation for unequal variances / sample sizes (i.e., unbalanced data)$$\nu \approx \frac{\left (\frac{s_{1}^{2}}{n_1}+\frac{s_{2}^{2}}{n_2}\right )^2}{\frac{s_{1}^{4}}{n_1(n_1-1)}+\frac{s_{2}^{4}}{n_2(n_2-1)}}$$

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