Define a Parameter $\mu$ By $\mu = \sum _ { i = 1 } ^ { J } \mu _ { i } / I$

Short Answer

Define a parameter $\mu$ by $\mu = \sum _ { i = 1 } ^ { J } \mu _ { i } / I$ and the parameters $\alpha _ { 1 } , \ldots \ldots \ldots , \alpha _ { j }$ by $\alpha _ { i } = \mu _ { i} - \mu$ . Then, $\sum _ { i = 1 } ^ { 3 } \alpha _ { i } =$ __________.