Sum-to-zero constraints in a two-way ANOVA model











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I'm reviewing my lecture notes on sum-to-zero constraints and I am having a tough time understanding the concept.



Say the constraints are $sum_{i=1}^{a} alpha_i = 0$, $sum_{j=1}^{b} beta_j = 0$, $sum_{i=1}^{a} (alpha beta)_{ij} = 0$ for $j = 1,...,b$ and $sum_{j=1}^{b} (alpha beta)_{ij} = 0$ for $i = 1,...,a$.



Here are the following questions I have:



1) Why does this represent $a + b + 1$ independent constraints and not $a + b + 2$ independent constraints?



2) How do I determine that there are $a-1$ linearly independent $alpha_i$'s, $b-1$ linearly independent $beta_j$'s and $(a-1)(b-1)$ linearly independent $(alpha beta ) _{ij}$'s?



Thanks in advance.










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    up vote
    1
    down vote

    favorite












    I'm reviewing my lecture notes on sum-to-zero constraints and I am having a tough time understanding the concept.



    Say the constraints are $sum_{i=1}^{a} alpha_i = 0$, $sum_{j=1}^{b} beta_j = 0$, $sum_{i=1}^{a} (alpha beta)_{ij} = 0$ for $j = 1,...,b$ and $sum_{j=1}^{b} (alpha beta)_{ij} = 0$ for $i = 1,...,a$.



    Here are the following questions I have:



    1) Why does this represent $a + b + 1$ independent constraints and not $a + b + 2$ independent constraints?



    2) How do I determine that there are $a-1$ linearly independent $alpha_i$'s, $b-1$ linearly independent $beta_j$'s and $(a-1)(b-1)$ linearly independent $(alpha beta ) _{ij}$'s?



    Thanks in advance.










    share|cite|improve this question


























      up vote
      1
      down vote

      favorite









      up vote
      1
      down vote

      favorite











      I'm reviewing my lecture notes on sum-to-zero constraints and I am having a tough time understanding the concept.



      Say the constraints are $sum_{i=1}^{a} alpha_i = 0$, $sum_{j=1}^{b} beta_j = 0$, $sum_{i=1}^{a} (alpha beta)_{ij} = 0$ for $j = 1,...,b$ and $sum_{j=1}^{b} (alpha beta)_{ij} = 0$ for $i = 1,...,a$.



      Here are the following questions I have:



      1) Why does this represent $a + b + 1$ independent constraints and not $a + b + 2$ independent constraints?



      2) How do I determine that there are $a-1$ linearly independent $alpha_i$'s, $b-1$ linearly independent $beta_j$'s and $(a-1)(b-1)$ linearly independent $(alpha beta ) _{ij}$'s?



      Thanks in advance.










      share|cite|improve this question















      I'm reviewing my lecture notes on sum-to-zero constraints and I am having a tough time understanding the concept.



      Say the constraints are $sum_{i=1}^{a} alpha_i = 0$, $sum_{j=1}^{b} beta_j = 0$, $sum_{i=1}^{a} (alpha beta)_{ij} = 0$ for $j = 1,...,b$ and $sum_{j=1}^{b} (alpha beta)_{ij} = 0$ for $i = 1,...,a$.



      Here are the following questions I have:



      1) Why does this represent $a + b + 1$ independent constraints and not $a + b + 2$ independent constraints?



      2) How do I determine that there are $a-1$ linearly independent $alpha_i$'s, $b-1$ linearly independent $beta_j$'s and $(a-1)(b-1)$ linearly independent $(alpha beta ) _{ij}$'s?



      Thanks in advance.







      linear-algebra statistics






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      edited Nov 26 at 22:37









      Davide Giraudo

      124k16150258




      124k16150258










      asked Nov 18 at 8:16









      angleofaxis

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