* DESCRIPTIVES:: Descriptive statistics.
* FREQUENCIES:: Frequency tables.
* EXAMINE:: Testing data for normality.
+* CORRELATIONS:: Correlation tables.
* CROSSTABS:: Crosstabulation tables.
+* FACTOR:: Factor analysis and Principal Components analysis
* NPAR TESTS:: Nonparametric tests.
* T-TEST:: Test hypotheses about means.
* ONEWAY:: One way analysis of variance.
there are many distinct values, then @cmd{EXAMINE} will produce a very
large quantity of output.
+@node CORRELATIONS
+@section CORRELATIONS
+
+@vindex CORRELATIONS
+@display
+CORRELATIONS
+ /VARIABLES = varlist [ WITH varlist ]
+ [
+ .
+ .
+ .
+ /VARIABLES = varlist [ WITH varlist ]
+ /VARIABLES = varlist [ WITH varlist ]
+ ]
+
+ [ /PRINT=@{TWOTAIL, ONETAIL@} @{SIG, NOSIG@} ]
+ [ /STATISTICS=DESCRIPTIVES XPROD ALL]
+ [ /MISSING=@{PAIRWISE, LISTWISE@} @{INCLUDE, EXCLUDE@} ]
+@end display
+
+@cindex correlation
+The @cmd{CORRELATIONS} procedure produces tables of the Pearson correlation coefficient
+for a set of variables. The significance of the coefficients are also given.
+
+At least one VARIABLES subcommand is required. If the WITH keyword is used, then a non-square
+correlation table will be produced.
+The variables preceding WITH, will be used as the rows of the table, and the variables following
+will be the columns of the table.
+If no WITH subcommand is given, then a square, symmetrical table using all variables is produced.
+
+
+The @cmd{MISSING} subcommand determines the handling of missing variables.
+If INCLUDE is set, then user-missing values are included in the
+calculations, but system-missing values are not.
+If EXCLUDE is set, which is the default, user-missing
+values are excluded as well as system-missing values.
+This is the default.
+
+If LISTWISE is set, then the entire case is excluded from analysis
+whenever any variable specified in any @cmd{/VARIABLES} subcommand
+contains a missing value.
+If PAIRWISE is set, then a case is considered missing only if either of the
+values for the particular coefficient are missing.
+The default is PAIRWISE.
+
+The PRINT subcommand is used to control how the reported significance values are printed.
+If the TWOTAIL option is used, then a two-tailed test of significance is
+printed. If the ONETAIL option is given, then a one-tailed test is used.
+The default is TWOTAIL.
+
+If the NOSIG option is specified, then correlation coefficients with significance less than
+0.05 are highlighted.
+If SIG is specified, then no highlighting is performed. This is the default.
+
+@cindex covariance
+The STATISTICS subcommand requests additional statistics to be displayed. The keyword
+DESCRIPTIVES requests that the mean, number of non-missing cases, and the non-biased
+estimator of the standard deviation are displayed.
+These statistics will be displayed in a separated table, for all the variables listed
+in any /VARIABLES subcommand.
+The XPROD keyword requests cross-product deviations and covariance estimators to
+be displayed for each pair of variables.
+The keyword ALL is the union of DESCRIPTIVES and XPROD.
@node CROSSTABS
@section CROSSTABS
Fixes for any of these deficiencies would be welcomed.
+@node FACTOR
+@section FACTOR
+
+@vindex FACTOR
+@cindex factor analysis
+@cindex principal components analysis
+@cindex principal axis factoring
+@cindex data reduction
+
+@display
+FACTOR VARIABLES=var_list
+
+ [ /METHOD = @{CORRELATION, COVARIANCE@} ]
+
+ [ /EXTRACTION=@{PC, PAF@}]
+
+ [ /PRINT=[INITIAL] [EXTRACTION] [UNIVARIATE] [CORRELATION] [COVARIANCE] [DET] [SIG] [ALL] [DEFAULT] ]
+
+ [ /PLOT=[EIGEN] ]
+
+ [ /FORMAT=[SORT] [BLANK(@var{n})] [DEFAULT] ]
+
+ [ /CRITERIA=[FACTORS(@var{n})] [MINEIGEN(@var{l})] [ITERATE(@var{m})] [ECONVERGE (@var{delta})] [DEFAULT] ]
+
+ [ /MISSING=[@{LISTWISE, PAIRWISE@}] [@{INCLUDE, EXCLUDE@}] ]
+@end display
+
+The FACTOR command performs Factor Analysis or Principal Axis Factoring on a dataset. It may be used to find
+common factors in the data or for data reduction purposes.
+
+The VARIABLES subcommand is required. It lists the variables which are to partake in the analysis.
+
+The /EXTRACTION subcommand is used to specify the way in which factors (components) are extracted from the data.
+If PC is specified, then Principal Components Analysis is used. If PAF is specified, then Principal Axis Factoring is
+used. By default Principal Components Analysis will be used.
+
+The /METHOD subcommand should be used to determine whether the covariance matrix or the correlation matrix of the data is
+to be analysed. By default, the correlation matrix is analysed.
+
+The /PRINT subcommand may be used to select which features of the analysis are reported:
+
+@itemize
+@item UNIVARIATE
+ A table of mean values, standard deviations and total weights are printed.
+@item INITIAL
+ Initial communalities and eigenvalues are printed.
+@item EXTRACTION
+ Extracted communalities and eigenvalues are printed.
+@item CORRELATION
+ The correlation matrix is printed.
+@item COVARIANCE
+ The covariance matrix is printed.
+@item DET
+ The determinant of the correlation or covariance matrix is printed.
+@item SIG
+ The significance of the elements of correlation matrix is printed.
+@item ALL
+ All of the above are printed.
+@item DEFAULT
+ Identical to INITIAL and EXTRACTION.
+@end itemize
+
+If /PLOT=EIGEN is given, then a ``Scree'' plot of the eigenvalues will be printed. This can be useful for visualising
+which factors (components) should be retained.
+
+The /FORMAT subcommand determined how data are to be displayed in loading matrices. If SORT is specified, then the variables
+are sorted in descending order of significance. If BLANK(@var{n}) is specified, then coefficients whose absolute value is less
+than @var{n} will not be printed. If the keyword DEFAULT is given, or if no /FORMAT subcommand is given, then no sorting is
+performed, and all coefficients will be printed.
+
+The /CRITERIA subcommand is used to specify how the number of extracted factors (components) are chosen. If FACTORS(@var{n}) is
+specified, where @var{n} is an integer, then @var{n} factors will be extracted. Otherwise, the MINEIGEN setting will
+be used. MINEIGEN(@var{l}) requests that all factors whose eigenvalues are greater than or equal to @var{l} are extracted.
+The default value of @var{l} is 1. The ECONVERGE and ITERATE settings have effect only when iterative algorithms for factor
+extraction (such as Principal Axis Factoring) are used. ECONVERGE(@var{delta}) specifies that iteration should cease when
+the maximum absolute value of the communality estimate between one iteration and the previous is less than @var{delta}. The
+default value of @var{delta} is 0.001.
+The ITERATE(@var{m}) setting sets the maximum number of iterations to @var{m}. The default value of @var{m} is 25.
+
+The @cmd{MISSING} subcommand determines the handling of missing variables.
+If INCLUDE is set, then user-missing values are included in the
+calculations, but system-missing values are not.
+If EXCLUDE is set, which is the default, user-missing
+values are excluded as well as system-missing values.
+This is the default.
+If LISTWISE is set, then the entire case is excluded from analysis
+whenever any variable specified in the @cmd{VARIABLES} subcommand
+contains a missing value.
+If PAIRWISE is set, then a case is considered missing only if either of the
+values for the particular coefficient are missing.
+The default is LISTWISE.
+
+
@node NPAR TESTS
@section NPAR TESTS