
SIEVE PLOTName:
We can define the following values for the contingency table:
When the two variables are independent, then the expected frequency is:
In a sieve plot, each m_{ij} is represented by a rectangle. The width of the rectangle is proportional to the total frequency in each column, n_{+j} and the height is proportional to the total frequency in each row, n_{i+}. The area of the rectangle is then proportional to m_{ij}. Each rectangle is then crossruled based on the observed frequency. The deviations from independence are reflected in the density of the shading. Denser shading indicates the observed frequency is greater than expected and sparse shading indicates the observed frequency is less than expected. As an additional cue, positive and negative departures from independence can be coded with different colors.
where <y1> is the first response variable; <y2> is the second response variable; and where the <SUBSET/EXCEPT/FOR qualification> is optional. This syntax is used for the case where you have raw data (i.e., the data has not yet been cross tabulated into a twoway table).
where <m> is a matrix containing the twoway table; and where the <SUBSET/EXCEPT/FOR qualification> is optional. This syntax is used for the case where we the data have already been crosstabulated into a twoway contingency table.
where <n11> is a parameter containing the value for row 1, column 1 of a 2x2 table; <n12> is a parameter containing the value for row 1, column 2 of a 2x2 table; <n21> is a parameter containing the value for row 2, column 1 of a 2x2 table; and <n22> is a parameter containing the value for row 2, column 2 of a 2x2 table. This syntax is used for the special case where you have a 2x2 table. In this case, you can enter the 4 values directly, although you do need to be careful that the parameters are entered in the order expected above.
SIEVE PLOT M SIEVE PLOT N11 N12 N21 N22
Although the program example below uses the TIC MARK LABEL commands to generate row and column labels, you may need to use the LEGEND or TEXT command to obtain more accurately centered labels.
Riedwyl and Schupbach (1994), "Parquet Diagram to Plot Contingency Tables". In Faulbaum, editor, "Softstat '93: Advances In Statistical Software", pp. 293299, Gustav Fischer, New York.
. Hair and Eye Color Data from page 61 of Friendly read matrix m 5 29 14 16 15 54 14 10 20 84 17 94 68 119 26 7 end of data . label case asis tic mark label case asis title case asis title offset 2 . x3label title Sieve Plot y1label displacement 12 y1label Eye Color x1label Hair Color tic offset units data xlimits 1 4 major xtic mark number 4 minor xtic mark number 0 xtic mark offset 0.5 0.5 x1tic mark label format alpha x1tic mark label content Black Brown Red Blond ylimits 1 4 major ytic mark number 4 minor ytic mark number 0 ytic mark offset 0.5 0.5 y1tic mark label format alpha y1tic mark label content Green Hazel Blue Brown y1tic mark label justification right . line solid solid dash line color black blue green . sieve plot m
 
Date created: 12/08/2008 Last updated: 12/04/2023 Please email comments on this WWW page to alan.heckert@nist.gov. 