st: working with a vector and scalars

["Cathy L. Antonakos" <cathya@umich.edu>]

I am working with scalars and a vector to estimate sample mean reliability by group, using a formula from Bryk & Raudenbush (1992) Hierarchical Linear Models:

lambda-j = t / [ t / (d /Nj)]

lambda-j is the reliability estimate for group j, t is between-group variance, d is within-group variance, and Nj is the group N.

Nj is a vector. The other parameters (t, d) are scalars.

Here's what I tried using -matrix- and -scalar-. The vector comes from a collapsed dataset. The scalars come from -loneway- using the original (uncollapsed) dataset. I have no trouble producing the vector and scalars, but can't figure out how to get them into the same matrix or file together so I can calculate the reliability esimates.

Any help will be much appreciated.

Cathy Antonakos

--------------
. bys placeXhr: egen N = count(crowdindx)
. preserve
. collapse (max) N, by(placeXhr)
. mkmat N
. levelsof placeXhr, local(l)
. matrix rownames N = `l' 
. matrix list N

N[49,1]
        N
2_10    2
2_11   81
2_12  150
2_13  340
2_14  138
2_15   82
2_16  102
2_17  119
2_18  288
2_19  160
 2_8   48
 2_9  265
3_10  166
3_11   71
3_12   63
3_13   25
3_14   53
3_15   68
3_16   44
3_17   61
3_18   33
3_19   35
 3_8   36
 3_9   16
6_10   33
6_11   69
6_12   82
6_13   30
6_14   87
6_15   90
6_16   90
6_17   92
6_18   63
6_19   79
 6_8   86
 6_9   41
9_10   57
9_11  135
9_12  113
9_13   83
9_14  152
9_15  168
9_16  160
9_17  151
9_18   97
9_19  147
 9_8  216
 9_9  166
 9_9  190

. restore

. *create matrices from -loneway- parameter estimates.
. preserve
. loneway crowdindx placeXhr

     One-way Analysis of Variance for crowdindx: Crowding Index (wtd. sum)

                                              Number of obs =      5121
                                                  R-squared =    0.5384

    Source                SS         df      MS            F     Prob > F
-------------------------------------------------------------------------
Between placeXhr       682650.69     47    14524.483    125.87     0.0000
Within placeXhr        585364.53   5073    115.38824
-------------------------------------------------------------------------
Total                  1268015.2   5120    247.65922

         Intraclass       Asy.
         correlation      S.E.       [95% Conf. Interval]
         ------------------------------------------------
            0.54152     0.06135       0.42126     0.66177

         Estimated SD of placeXhr effect         11.67412
         Estimated SD within placeXhr            10.74189
         Est. reliability of a placeXhr mean      0.99206
              (evaluated at n=105.73)

. return list

scalars:
                 r(lb) =  .4212643949911408
                 r(ub) =  .6617675540515819
                 r(se) =  .0613539740927638
               r(sd_w) =  10.74189173110937
               r(sd_b) =  11.67412402231762
              r(rho_t) =  .9920556043556278
                r(rho) =  .5415159745213614
                  r(N) =  5121

. scalar t = r(sd_b) * r(sd_b) 
. scalar s = r(sd_w) * r(sd_w)
. restore

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/