The number of degrees of freedom for a two-way contingency table with I rows and J columns is
A) $I \cdot J$
B) $( I - 1 ) \cdot J$
C) $I \cdot ( J - 1 )$
D) $( I - 1 ) \cdot ( J - 1 )$
E) $I + J - 1$

Question

Quizplus · Accepted Answer

The degrees of freedom for a two-way contingency table with I rows and J columns is calculated as $(I - 1) \cdot (J - 1)$. This formula accounts for the constraints that reduce the number of independent values in the table.

The Number of Degrees of Freedom for a Two-Way Contingency I⋅JI \cdot JI⋅J

The Number of Degrees of Freedom for a Two-Way Contingency $I \cdot J$