29.07.2014 Views

Practical Considerations in Raking Survey Data

Practical Considerations in Raking Survey Data

Practical Considerations in Raking Survey Data

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

weights of the n <strong>in</strong>dividual respondents. Thus, the basic rak<strong>in</strong>g algorithm is described <strong>in</strong> terms of<br />

those <strong>in</strong>dividual weights, w, i = 1,2,..., n.<br />

For an unweighted (i.e., equally weighted) sample, one<br />

i<br />

can simply take the <strong>in</strong>itial weights to be w = 1 for each i.<br />

i<br />

In a cross-classification that has J rows and K columns, denote the sum of the<br />

wi<br />

<strong>in</strong> cell ( j, k)<br />

by<br />

w . jk<br />

To <strong>in</strong>dicate further summation, replace a subscript by a + sign. Thus, the <strong>in</strong>itial row totals<br />

and column totals of the sample weights are<br />

w<br />

j +<br />

and<br />

correspond<strong>in</strong>g population control totals by T +<br />

and .<br />

j<br />

T + k<br />

w + k<br />

, respectively. Analogously, denote the<br />

The iterative rak<strong>in</strong>g algorithm produces modified weights, whose sums are denoted by a suitably<br />

subscripted m with a parenthesized superscript for the number of the step. Thus, <strong>in</strong> the twovariable<br />

cross-classification<br />

m (1) jk<br />

denotes the sum of the modified weights <strong>in</strong> cell (j,k) at the end<br />

of Step 1. If one beg<strong>in</strong>s by match<strong>in</strong>g the control totals for the rows,<br />

algorithm are<br />

T<br />

j +<br />

, the <strong>in</strong>itial steps of the<br />

m<br />

(0)<br />

jk<br />

= w<br />

(j = 1,...,J; k=1,...,K)<br />

jk<br />

m = m ( T / m )<br />

(for each k with<strong>in</strong> each j)<br />

(1) (0) (0)<br />

jk jk j+ j+<br />

m = m ( T / m )<br />

(for each j with<strong>in</strong> each k)<br />

(2) (1) (1)<br />

jk jk + k + k<br />

6

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!