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Table 2 Degrees of freedom associated with common statistical tests.

From: The problem of pseudoreplication in neuroscientific studies: is it affecting your analysis?

Test

Degrees of Freedom

T-test

 

   Independent

n1 + n2 - 2

   Paired

n - 1

One-way ANOVA

G - 1 and n - G

Two-way Anova

 

   Main effect of A

G A -1

   Main effect of B

G B -1

   A × B interaction

(GA -1)(GB -1)

   Error

n - G A G B

One-way RM-Anova

 

   Between subjects

G - 1

   Error

(n -1)(G -1)

Two-way Mixed † ANOVA

 

   Between subjects

n(G - 1)

Groups

   G-1

Error

   G(n-1)

   Within subjects

N - nG

Obs

   Obs - 1

Group × Obs Interaction

   (G - 1)(Obs - 1)

Error

   N - nG - G (Obs - 1)

Linear Regression

1 and n - 2

Chi-square

(R - 1)(C -1)

  1. n1 = sample size of group one; n2 = sample size of group two; n = total sample size; N = total number of observations (equal to n × Obs); G = number of groups; G A = number of groups for Factor A; G B = number of groups for Factor B; Obs = number of repeated observations on the same subject; R = number of rows; C = number or columns. † "Mixed" refers to the presence of both between and within subjects effects, and should not be confused with mixed effects models described in the text.
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BMC Neuroscience

ISSN: 1471-2202

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