Page 163 - Applied Statistics with R
P. 163

9.2. SAMPLING DISTRIBUTION                                        163



                                            00       01      02  ⋯      0(  −1)
                                       ⎡                        ⋯            ⎤
                                       ⎢   10      11      12          1(  −1)  ⎥
                                     =  ⎢     20     21      22  ⋯      2(  −1) ⎥  .
                                       ⎢   ⋮       ⋮       ⋮            ⋮    ⎥
                                       ⎣    (  −1)0     (  −1)1     (  −1)2  ⋯     (  −1)(  −1)⎦

                      Essentially, the diagonal elements correspond to the    vector.
                                                    ̂
                      Then the standard error for the    vector is given by

                                                   ̂
                                                             ⊤
                                               SE[  ] =       √ (     ) −1
                      and for a particular       ̂


                                                      ̂
                                                 SE[   ] =    √   .
                                                                  
                                                       
                                                            
                                        ̂
                      Lastly, each of the    follows a normal distribution,
                                          
                                                  ̂
                                                            2
                                                   ∼    (   ,       ) .
                                                   
                                                           
                                                                  
                      thus
                                                    ̂
                                                     −      
                                                     
                                                     √         ∼      −   .
                                                     
                      Now that we have the necessary distributional results, we can move on to per-
                      form tests and make interval estimates.


                      9.2.1   Single Parameter Tests

                      The first test we will see is a test for a single    .
                                                                 

                                               ∶    = 0  vs    ∶    ≠ 0
                                                             1
                                                   
                                              0
                                                                   
                      Again, the test statistic takes the form
                                                      EST − HYP
                                                TS =             .
                                                          SE
                      In particular,
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