The CORRESP Procedure

is equivalent to specifying the OBSERVED, RP, CP, CELLCHI2, EXPECTED, and DEVIATION options. Specifying the ALL option does not affect the PRINT= option. Therefore, only frequencies (not percentages) for these options are displayed unless you specify otherwise with the PRINT= option.

displays adjusted inertias when you are performing multiple correspondence analysis. By default, unadjusted inertias (the usual inertias from multiple correspondence analysis) are displayed. However, adjusted inertias that use a method proposed by Benzécri (1979) and described by Greenacre (1984, p. 145) can be displayed by specifying the BENZECRI option. Specify the UNADJUSTED option to output the usual table of unadjusted inertias as well. For more information, see the section MCA Adjusted Inertias.

enables you to create binary tables easily. When you specify the BINARY option, specify only column variables in the TABLES statement. Each input data set observation forms a single row in the constructed table.

enables you to create a Burt matrix for MCA by using an in-memory algorithm and a single pass through the data. The default Burt matrix construction method might use a utility file, which can be slow for large data sets. The algorithm that this option uses is usually faster than the default algorithm, particularly for large data sets. However, it does not sort the levels (the Burt matrix rows and columns) within the categorical variables.

displays the contribution to the total chi-square test statistic for each cell. See also the descriptions of the DEVIATION, EXPECTED, and OBSERVED options.

displays the chi-square p-value in the inertia and chi-square decomposition table. The chi-square p-value is not displayed by default because in many cases the table being analyzed is not a true two-way contingency table.

provides other standardizations of the column coordinates. The COLUMN= option is rarely needed. Typically, you should use the PROFILE= option instead (see the section The PROFILE=, ROW=, and COLUMN= Options). By default, COLUMN=DBD.

displays the column profile matrix. Column profiles contain the observed conditional probabilities of row membership given column membership. See also the RP option.

specifies the method of crossing (factorially combining) the levels of the TABLES variables. The default is CROSS=NONE.

The section TABLES Statement provides a more detailed description of this option.

specifies the SAS data set to be used by PROC CORRESP. If you do not specify the DATA= option, PROC CORRESP uses the most recently created SAS data set.

displays the matrix of deviations between the observed frequency matrix and the product of its row marginals and column marginals divided by its grand frequency. For ordinary two-way contingency tables, these are the observed minus expected frequencies under the hypothesis of row and column independence and are components of the chi-square test statistic. See also the CELLCHI2, EXPECTED, and OBSERVED options.

specifies the number of dimensions or axes to use. The default is DIMENS=2. The maximum value of the DIMENS= option in an table is or , whichever is smaller. For example, in a table with 4 rows and 5 columns, the maximum specification is DIMENS=3. If your table has 2 rows or 2 columns, specify DIMENS=1.

displays the product of the row marginals and the column marginals divided by the grand frequency of the observed frequency table. For ordinary two-way contingency tables, these are the expected frequencies under the hypothesis of row and column independence and are components of the chi-square test statistic. In other situations, this interpretation is not strictly valid. See also the CELLCHI2, DEVIATION, and OBSERVED options.

indicates that the PROC CORRESP input data set has the same form as an output data set from the FREQ procedure, even if it was not directly produced by PROC FREQ. The FREQOUT option enables PROC CORRESP to take shortcuts in constructing the contingency table.

When you specify the FREQOUT option, you must also specify a WEIGHT statement. The cell frequencies in a PROC FREQ output data set are contained in a variable called COUNT, so specify COUNT in a WEIGHT statement with PROC CORRESP. The FREQOUT option might produce unexpected results if the DATA= data set is structured incorrectly. Each of the two variable lists specified in the TABLES statement must consist of a single variable, and observations must be grouped by the levels of the row variable and then by the levels of the column variable. It is not required that the observations be sorted by the row variable and column variable, but they must be grouped consistently. There must be as many observations in the input data set (or BY group) as there are cells in the completed contingency table. Zero cells must be specified with zero weights. When you use PROC FREQ to create the PROC CORRESP input data set, you must specify the SPARSE option in the FREQ procedure’s TABLES statement so that the zero cells are written to the output data set.

displays adjusted inertias when you are performing multiple correspondence analysis. By default, unadjusted inertias (the usual inertias from multiple correspondence analysis) are displayed. However, adjusted inertias that use a method proposed by Greenacre (1984, p. 156) can be displayed by specifying the GREENACRE option. Specify the UNADJUSTED option to output the usual table of unadjusted inertias as well. For more information, see the section MCA Adjusted Inertias.

displays the inertia and chi-square decomposition table in addition to the inertia and chi-square decomposition chart when ODS Graphics is enabled. This table is produced by default when ODS Graphics is not enabled or when the chart is not produced. When ODS Graphics is enabled:

requests a multiple correspondence analysis. This option requires that the input table be a Burt table, which is a symmetric matrix of crosstabulations among several categorical variables. If you specify the MCA option and a VAR statement, you must also specify the NVARS= option, which gives the number of categorical variables that were used to create the table. With raw categorical data, if you want results for the individuals as well as the categories, use the BINARY option instead.

specifies the minimum inertia used to create the "best" tables—the indicator of which points best explain the inertia of each dimension. By default, MININERTIA=0.8. For more information, see the section Algorithm and Notation.

specifies that observations with missing values for the TABLES statement variables are included in the analysis. Missing values are treated as a distinct level of each categorical variable. By default, observations with missing values are excluded from the analysis.

suppresses the display of the column coordinates and statistics and omits them from the output coordinate data set.

suppresses the display of all output. This option is useful when you need only an output data set. This option disables the Output Delivery System (ODS), including ODS Graphics, for the duration of the PROC. For more information, see Chapter 23, Using the Output Delivery System.

suppresses the display of the row coordinates and statistics and omits them from the output coordinate data set.

The NOROW option can be useful when the rows of the contingency table are replications.

specifies the number of classification variables that were used to create the Burt table. For example, suppose the Burt table was originally created with the following statement:

tables a b c;

You must specify NVARS=3 to read the table with a VAR statement.

The NVARS= option is required when you specify both the MCA option and a VAR statement. (See the section VAR Statement for an example.)

displays the contingency table of observed frequencies and its row, column, and grand totals. If you do not specify the OBSERVED or ALL option, the contingency table is not displayed.

creates an output coordinate SAS data set to contain the row, column, supplementary observation, and supplementary variable coordinates. This data set also contains the masses, squared cosines, quality of each point’s representation in the DIMENS=n dimensional display, relative inertias, partial contributions to inertia, and best indicators.

creates an output frequency SAS data set to contain the contingency table, row, and column profiles, the expected values, and the observed minus expected values and contributions to the chi-square statistic.

specifies options that control the details of the plots. When you specify only one plot request, you can omit the parentheses around the plot request.

ODS Graphics must be enabled before plots can be requested. For example:

ods graphics on;

proc corresp;
   tables Marital, Origin;
run;

ods graphics off;

For more information about enabling and disabling ODS Graphics, see the section Enabling and Disabling ODS Graphics in Chapter 24, Statistical Graphics Using ODS.

By default, for simple correspondence analysis, PROC CORRESP prints the configuration of points consisting of the row coordinates and column coordinates. With MCA, only column coordinates are printed. The default plots (y * x) are Dim2 * Dim1, Dim3 * Dim1, Dim3 * Dim2, and so on. When you specify PLOTS(FLIP), the plots are Dim1 * Dim2, Dim1 * Dim3, Dim2 * Dim3, and so on.

The global-plot-options are as follows:

The plot-requests include the following:

affects the OBSERVED, RP, CP, CELLCHI2, EXPECTED, and DEVIATION options. The default is PRINT=FREQ.

specifies the standardization for the row and column coordinates. The default is PROFILE=BOTH.

provides other standardizations of the row coordinates. The ROW= option is rarely needed. Typically, you should use the PROFILE= option instead (see the section The PROFILE=, ROW=, and COLUMN= Options). By default, ROW=DAD.

displays the row profile matrix. Row profiles contain the observed conditional probabilities of column membership given row membership. See also the CP option.

suppresses the display of all point and coordinate statistics except the coordinates. The following information is suppressed: each point’s mass, relative contribution to the total inertia, and quality of representation in the DIMENS=n dimensional display; the squared cosines of the angles between each axis and a vector from the origin to the point; the partial contributions of each point to the inertia of each dimension; and the best indicators.

specifies the largest value that is considered to be within rounding error of zero. The default value is 1E–8. This parameter is used in checking for zero rows and columns, in checking Burt table diagonal sums for equality, in checking denominators before dividing, and so on. Typically, you should not assign a value outside the range 1E–6 to 1E–12.

adds the variable _VAR_, which contains the name or label of the variable corresponding to the current level, to the OUTC= and OUTF= data sets.

displays unadjusted inertias when you are performing multiple correspondence analysis. By default, unadjusted inertias (the usual inertias from multiple correspondence analysis) are displayed. However, if adjusted inertias are requested by either the GREENACRE option or the BENZECRI option, then the unadjusted inertia table is not displayed unless the UNADJUSTED option is specified.^[33] For more information, see the section MCA Adjusted Inertias.