* EXAMINE:: Testing data for normality.
* CORRELATIONS:: Correlation tables.
* CROSSTABS:: Crosstabulation tables.
-* FACTOR:: Factor analysis and Principal Components analysis
+* FACTOR:: Factor analysis and Principal Components analysis.
+* LOGISTIC REGRESSION:: Bivariate Logistic Regression.
* MEANS:: Average values and other statistics.
* NPAR TESTS:: Nonparametric tests.
* T-TEST:: Test hypotheses about means.
All other subcommands are optional:
The @subcmd{MISSING} subcommand determines the handling of missing variables. If
-INCLUDE is set, then user-missing values are included in the
-calculations. If NOINCLUDE is set, which is the default, user-missing
-values are excluded. If VARIABLE is set, then missing values are
-excluded on a variable by variable basis; if LISTWISE is set, then
+@subcmd{INCLUDE} is set, then user-missing values are included in the
+calculations. If @subcmd{NOINCLUDE} is set, which is the default, user-missing
+values are excluded. If @subcmd{VARIABLE} is set, then missing values are
+excluded on a variable by variable basis; if @subcmd{LISTWISE} is set, then
the entire case is excluded whenever any value in that case has a
-system-missing or, if INCLUDE is set, user-missing value.
+system-missing or, if @subcmd{INCLUDE} is set, user-missing value.
The @subcmd{FORMAT} subcommand affects the output format. Currently the
-LABELS/NOLABELS and NOINDEX/INDEX settings are not used. When SERIAL is
+@subcmd{LABELS/NOLABELS} and @subcmd{NOINDEX/INDEX} settings are not used.
+When @subcmd{SERIAL} is
set, both valid and missing number of cases are listed in the output;
-when NOSERIAL is set, only valid cases are listed.
+when @subcmd{NOSERIAL} is set, only valid cases are listed.
The @subcmd{SAVE} subcommand causes @cmd{DESCRIPTIVES} to calculate Z scores for all
the specified variables. The Z scores are saved to new variables.
with Z prepended and truncated to a maximum of 8 characters, then the
names ZSC000 through ZSC999, STDZ00 through STDZ09, ZZZZ00 through
ZZZZ09, ZQZQ00 through ZQZQ09, in that sequence. In addition, Z score
-variable names can be specified explicitly on VARIABLES in the variable
+variable names can be specified explicitly on @subcmd{VARIABLES} in the variable
list by enclosing them in parentheses after each variable.
+When Z scores are calculated, @pspp{} ignores @cmd{TEMPORARY},
+treating temporary transformations as permanent.
The @subcmd{STATISTICS} subcommand specifies the statistics to be displayed:
@table @code
-@item ALL
+@item @subcmd{ALL}
All of the statistics below.
-@item MEAN
+@item @subcmd{MEAN}
Arithmetic mean.
-@item SEMEAN
+@item @subcmd{SEMEAN}
Standard error of the mean.
-@item STDDEV
+@item @subcmd{STDDEV}
Standard deviation.
-@item VARIANCE
+@item @subcmd{VARIANCE}
Variance.
-@item KURTOSIS
+@item @subcmd{KURTOSIS}
Kurtosis and standard error of the kurtosis.
-@item SKEWNESS
+@item @subcmd{SKEWNESS}
Skewness and standard error of the skewness.
-@item RANGE
+@item @subcmd{RANGE}
Range.
@item MINIMUM
Minimum value.
@end table
The @subcmd{SORT} subcommand specifies how the statistics should be sorted. Most
-of the possible values should be self-explanatory. NAME causes the
+of the possible values should be self-explanatory. @subcmd{NAME} causes the
statistics to be sorted by name. By default, the statistics are listed
-in the order that they are specified on the @subcmd{VARIABLES} subcommand. The A
-and D settings request an ascending or descending sort order,
-respectively.
+in the order that they are specified on the @subcmd{VARIABLES} subcommand.
+The @subcmd{A} and @subcmd{D} settings request an ascending or descending
+sort order, respectively.
@node FREQUENCIES
@section FREQUENCIES
@end itemize
The @subcmd{MISSING} subcommand controls the handling of user-missing values.
-When EXCLUDE, the default, is set, user-missing values are not included
-in frequency tables or statistics. When INCLUDE is set, user-missing
+When @subcmd{EXCLUDE}, the default, is set, user-missing values are not included
+in frequency tables or statistics. When @subcmd{INCLUDE} is set, user-missing
are included. System-missing values are never included in statistics,
but are listed in frequency tables.
-The available STATISTICS are the same as available in @cmd{DESCRIPTIVES}
-(@pxref{DESCRIPTIVES}), with the addition of MEDIAN, the data's median
+The available @subcmd{STATISTICS} are the same as available
+in @cmd{DESCRIPTIVES} (@pxref{DESCRIPTIVES}), with the addition
+of @subcmd{MEDIAN}, the data's median
value, and MODE, the mode. (If there are multiple modes, the smallest
value is reported.) By default, the mean, standard deviation of the
mean, minimum, and maximum are reported for each variable.
@vindex EXAMINE
@cindex Exploratory data analysis
-@cindex Normality, testing for
+@cindex normality, testing
@display
EXAMINE
The @subcmd{VARIABLES} subcommand is mandatory.
It specifies the dependent variables and optionally variables to use as
factors for the analysis.
-Variables listed before the first BY keyword (if any) are the
+Variables listed before the first @subcmd{BY} keyword (if any) are the
dependent variables.
The dependent variables may optionally be followed by a list of
factors which tell @pspp{} how to break down the analysis for each
dependent variable.
Following the dependent variables, factors may be specified.
-The factors (if desired) should be preceeded by a single BY keyword.
+The factors (if desired) should be preceeded by a single @subcmd{BY} keyword.
The format for each factor is
@display
@var{factorvar} [BY @var{subfactorvar}].
The @subcmd{PERCENTILES} subcommand specifies which percentiles are to be calculated,
and which algorithm to use for calculating them. The default is to
calculate the 5, 10, 25, 50, 75, 90, 95 percentiles using the
-HAVERAGE algorithm.
+@subcmd{HAVERAGE} algorithm.
The @subcmd{TOTAL} and @subcmd{NOTOTAL} subcommands are mutually exclusive. If @subcmd{NOTOTAL}
is given and factors have been specified in the @subcmd{VARIABLES} subcommand,
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 @subcmd{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.
+At least one @subcmd{VARIABLES} subcommand is required. If the @subcmd{WITH}
+keyword is used, then a non-square correlation table will be produced.
+The variables preceding @subcmd{WITH}, will be used as the rows of the table,
+and the variables following will be the columns of the table.
If no @subcmd{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
+If @subcmd{INCLUDE} is set, then user-missing values are included in the
calculations, but system-missing values are not.
If @subcmd{EXCLUDE} is set, which is the default, user-missing
values are excluded as well as system-missing values.
-This is the default.
If @subcmd{LISTWISE} is set, then the entire case is excluded from analysis
whenever any variable specified in any @cmd{/VARIABLES} subcommand
@cindex covariance
The @subcmd{STATISTICS} subcommand requests additional statistics to be displayed. The keyword
-DESCRIPTIVES requests that the mean, number of non-missing cases, and the non-biased
+@subcmd{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 @subcmd{/VARIABLES} subcommand.
The @subcmd{XPROD} keyword requests cross-product deviations and covariance estimators to
be displayed for each pair of variables.
-The keyword ALL is the union of @subcmd{DESCRIPTIVES} and @subcmd{XPROD}.
+The keyword @subcmd{ALL} is the union of @subcmd{DESCRIPTIVES} and @subcmd{XPROD}.
@node CROSSTABS
@section CROSSTABS
TABLES. In integer mode, only numeric variables are allowed.
The @subcmd{MISSING} subcommand determines the handling of user-missing values.
-When set to TABLE, the default, missing values are dropped on a table by
-table basis. When set to INCLUDE, user-missing values are included in
-tables and statistics. When set to REPORT, which is allowed only in
+When set to @subcmd{TABLE}, the default, missing values are dropped on a table by
+table basis. When set to @subcmd{INCLUDE}, user-missing values are included in
+tables and statistics. When set to @subcmd{REPORT}, which is allowed only in
integer mode, user-missing values are included in tables but marked with
an @samp{M} (for ``missing'') and excluded from statistical
calculations.
crosstabulation tables to be displayed. It has a number of possible
settings:
-@itemize @subcmd{}
+@itemize @asis
@item
-TABLES, the default, causes crosstabulation tables to be output.
-NOTABLES suppresses them.
+@subcmd{TABLES}, the default, causes crosstabulation tables to be output.
+@subcmd{NOTABLES} suppresses them.
@item
@subcmd{PIVOT}, the default, causes each @subcmd{TABLES} subcommand to be displayed in a
@end table
@samp{/CELLS} without any settings specified requests @subcmd{COUNT}, @subcmd{ROW},
-@subcmd{COLUMN}, and @subcmd{TOTAL}. If CELLS is not specified at all then only @subcmd{COUNT}
+@subcmd{COLUMN}, and @subcmd{TOTAL}.
+If @subcmd{CELLS} is not specified at all then only @subcmd{COUNT}
will be selected.
The @subcmd{STATISTICS} subcommand selects statistics for computation:
@samp{/STATISTICS} without any settings selects CHISQ. If the
@subcmd{STATISTICS} subcommand is not given, no statistics are calculated.
-@strong{Please note:} Currently the implementation of CROSSTABS has the
-followings bugs:
+@strong{Please note:} Currently the implementation of @cmd{CROSSTABS} has the
+following bugs:
@itemize @bullet
@item
-Pearson's R (but not Spearman) is off a little.
-@item
-T values for Spearman's R and Pearson's R are wrong.
-@item
Significance of symmetric and directional measures is not calculated.
@item
-Asymmetric ASEs and T values for lambda are wrong.
-@item
-ASE of Goodman and Kruskal's tau is not calculated.
-@item
-ASE of symmetric somers' d is wrong.
+Asymptotic standard error is not calculated for asymmetric lambda,
+Goodman and Kruskal's tau, or symmetric Somers' d.
@item
-Approximate T of uncertainty coefficient is wrong.
+Approximate T is not calculated for symmetric uncertainty coefficient.
@end itemize
Fixes for any of these deficiencies would be welcomed.
[ /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
+The @cmd{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 @subcmd{VARIABLES} subcommand is required. It lists the variables which are to partake in the analysis.
The @subcmd{/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
+If @subcmd{PC} is specified, then Principal Components Analysis is used.
+If @subcmd{PAF} is specified, then Principal Axis Factoring is
used. By default Principal Components Analysis will be used.
The @subcmd{/ROTATION} subcommand is used to specify the method by which the extracted solution will be rotated.
-Three methods are available: VARIMAX (which is the default), EQUAMAX, and QUARTIMAX.
-If don't want any rotation to be performed, the word NOROTATE will prevent the command from performing any
+Three methods are available: @subcmd{VARIMAX} (which is the default), @subcmd{EQUAMAX}, and @subcmd{QUARTIMAX}.
+If don't want any rotation to be performed, the word @subcmd{NOROTATE} will prevent the command from performing any
rotation on the data. Oblique rotations are not supported.
The @subcmd{/METHOD} subcommand should be used to determine whether the covariance matrix or the correlation matrix of the data is
The @subcmd{/PRINT} subcommand may be used to select which features of the analysis are reported:
-@itemize @subcmd{}
-@item UNIVARIATE
+@itemize
+@item @subcmd{UNIVARIATE}
A table of mean values, standard deviations and total weights are printed.
-@item INITIAL
+@item @subcmd{INITIAL}
Initial communalities and eigenvalues are printed.
-@item EXTRACTION
+@item @subcmd{EXTRACTION}
Extracted communalities and eigenvalues are printed.
-@item ROTATION
+@item @subcmd{ROTATION}
Rotated communalities and eigenvalues are printed.
-@item CORRELATION
+@item @subcmd{CORRELATION}
The correlation matrix is printed.
-@item COVARIANCE
+@item @subcmd{COVARIANCE}
The covariance matrix is printed.
-@item DET
+@item @subcmd{DET}
The determinant of the correlation or covariance matrix is printed.
-@item KMO
+@item @subcmd{KMO}
The Kaiser-Meyer-Olkin measure of sampling adequacy and the Bartlett test of sphericity is printed.
-@item SIG
+@item @subcmd{SIG}
The significance of the elements of correlation matrix is printed.
-@item ALL
+@item @subcmd{ALL}
All of the above are printed.
-@item DEFAULT
- Identical to INITIAL and EXTRACTION.
+@item @subcmd{DEFAULT}
+ Identical to @subcmd{INITIAL} and @subcmd{EXTRACTION}.
@end itemize
If @subcmd{/PLOT=EIGEN} is given, then a ``Scree'' plot of the eigenvalues will be printed. This can be useful for visualizing
which factors (components) should be retained.
-The @subcmd{/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 @subcmd{/FORMAT} subcommand is given, then no sorting is
+The @subcmd{/FORMAT} subcommand determined how data are to be displayed in loading matrices. If @subcmd{SORT} is specified, then the variables
+are sorted in descending order of significance. If @subcmd{BLANK(@var{n})} is specified, then coefficients whose absolute value is less
+than @var{n} will not be printed. If the keyword @subcmd{DEFAULT} is given, or if no @subcmd{/FORMAT} subcommand is given, then no sorting is
performed, and all coefficients will be printed.
The @subcmd{/CRITERIA} subcommand is used to specify how the number of extracted factors (components) are chosen.
If @subcmd{FACTORS(@var{n})} is
specified, where @var{n} is an integer, then @var{n} factors will be extracted. Otherwise, the @subcmd{MINEIGEN} setting will
-be used. @subcmd{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 @subcmd{ECONVERGE} and @subcmd{ITERATE} settings have effect only when iterative algorithms for factor
-extraction (such as Principal Axis Factoring) are used. @subcmd{ECONVERGE(@var{delta})} specifies that
+be used.
+@subcmd{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 @subcmd{ECONVERGE} setting has effect only when iterative algorithms for factor
+extraction (such as Principal Axis Factoring) are used.
+@subcmd{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 @subcmd{ITERATE(@var{m})} setting sets the maximum number of iterations to @var{m}. The default value of @var{m} is 25.
+The @subcmd{ITERATE(@var{m})} may appear any number of times and is used for two different purposes.
+It is used to set the maximum number of iterations (@var{m}) for convergence and also to set the maximum number of iterations
+for rotation.
+Whether it affects convergence or rotation depends upon which subcommand follows the @subcmd{ITERATE} subcommand.
+If @subcmd{EXTRACTION} follows, it affects convergence.
+If @subcmd{ROTATION} follows, it affects rotation.
+If neither @subcmd{ROTATION} nor @subcmd{EXTRACTION} follow a @subcmd{ITERATE} subcommand it will be ignored.
+The default value of @var{m} is 25.
The @cmd{MISSING} subcommand determines the handling of missing variables.
If @subcmd{INCLUDE} is set, then user-missing values are included in the
values for the particular coefficient are missing.
The default is @subcmd{LISTWISE}.
+@node LOGISTIC REGRESSION
+@section LOGISTIC REGRESSION
+
+@vindex LOGISTIC REGRESSION
+@cindex logistic regression
+@cindex bivariate logistic regression
+
+@display
+LOGISTIC REGRESSION [VARIABLES =] @var{dependent_var} WITH @var{predictors}
+
+ [/CATEGORICAL = @var{categorical_predictors}]
+
+ [@{/NOCONST | /ORIGIN | /NOORIGIN @}]
+
+ [/PRINT = [SUMMARY] [DEFAULT] [CI(@var{confidence})] [ALL]]
+
+ [/CRITERIA = [BCON(@var{min_delta})] [ITERATE(@var{max_interations})]
+ [LCON(@var{min_likelihood_delta})] [EPS(@var{min_epsilon})]
+ [CUT(@var{cut_point})]]
+
+ [/MISSING = @{INCLUDE|EXCLUDE@}]
+@end display
+
+Bivariate Logistic Regression is used when you want to explain a dichotomous dependent
+variable in terms of one or more predictor variables.
+
+The minimum command is
+@example
+LOGISTIC REGRESSION @var{y} WITH @var{x1} @var{x2} @dots{} @var{xn}.
+@end example
+Here, @var{y} is the dependent variable, which must be dichotomous and @var{x1} @dots{} @var{xn}
+are the predictor variables whose coefficients the procedure estimates.
+
+By default, a constant term is included in the model.
+Hence, the full model is
+@math{
+{\bf y}
+= b_0 + b_1 {\bf x_1}
++ b_2 {\bf x_2}
++ \dots
++ b_n {\bf x_n}
+}
+
+Predictor variables which are categorical in nature should be listed on the @subcmd{/CATEGORICAL} subcommand.
+Simple variables as well as interactions between variables may be listed here.
+
+If you want a model without the constant term @math{b_0}, use the keyword @subcmd{/ORIGIN}.
+@subcmd{/NOCONST} is a synonym for @subcmd{/ORIGIN}.
+
+An iterative Newton-Raphson procedure is used to fit the model.
+The @subcmd{/CRITERIA} subcommand is used to specify the stopping criteria of the procedure,
+and other parameters.
+The value of @var{cut_point} is used in the classification table. It is the
+threshold above which predicted values are considered to be 1. Values
+of @var{cut_point} must lie in the range [0,1].
+During iterations, if any one of the stopping criteria are satisfied, the procedure is
+considered complete.
+The stopping criteria are:
+@itemize
+@item The number of iterations exceeds @var{max_iterations}.
+ The default value of @var{max_iterations} is 20.
+@item The change in the all coefficient estimates are less than @var{min_delta}.
+The default value of @var{min_delta} is 0.001.
+@item The magnitude of change in the likelihood estimate is less than @var{min_likelihood_delta}.
+The default value of @var{min_delta} is zero.
+This means that this criterion is disabled.
+@item The differential of the estimated probability for all cases is less than @var{min_epsilon}.
+In other words, the probabilities are close to zero or one.
+The default value of @var{min_epsilon} is 0.00000001.
+@end itemize
+
+
+The @subcmd{PRINT} subcommand controls the display of optional statistics.
+Currently there is one such option, @subcmd{CI}, which indicates that the
+confidence interval of the odds ratio should be displayed as well as its value.
+@subcmd{CI} should be followed by an integer in parentheses, to indicate the
+confidence level of the desired confidence interval.
+
+The @subcmd{MISSING} subcommand determines the handling of missing
+variables.
+If @subcmd{INCLUDE} is set, then user-missing values are included in the
+calculations, but system-missing values are not.
+If @subcmd{EXCLUDE} is set, which is the default, user-missing
+values are excluded as well as system-missing values.
+This is the default.
+
@node MEANS
@section MEANS
After each variable, @samp{A} or @samp{D} may appear, indicating that
the variable is to be ranked in ascending or descending order.
Ascending is the default.
-If a BY keyword appears, it should be followed by a list of variables
+If a @subcmd{BY} keyword appears, it should be followed by a list of variables
which are to serve as group variables.
In this case, the cases are gathered into groups, and ranks calculated
for each group.
default is to take the mean value of all the tied cases.
The @subcmd{FRACTION} subcommand specifies how proportional ranks are to be
-calculated. This only has any effect if NORMAL or PROPORTIONAL rank
+calculated. This only has any effect if @subcmd{NORMAL} or @subcmd{PROPORTIONAL} rank
functions are requested.
The @subcmd{PRINT} subcommand may be used to specify that a summary of the rank
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