* DESCRIPTIVES:: Descriptive statistics.
* FREQUENCIES:: Frequency tables.
* CROSSTABS:: Crosstabulation tables.
+* T-TEST:: Test Hypotheses about means.
@end menu
@node DESCRIPTIVES, FREQUENCIES, Statistics, Statistics
@code{/NTILES=4} would cause quartiles to be reported. In addition,
particular percentiles can be requested with the PERCENTILES subcommand.
-@node CROSSTABS, , FREQUENCIES, Statistics
+@node CROSSTABS, T-TEST, FREQUENCIES, Statistics
@section CROSSTABS
@display
number of dimensions is permitted, and any number of variables per
dimension is allowed. The TABLES subcommand may be repeated as many
times as needed. This is the only required subcommand in @dfn{general
-mode}.
+mode}.
Occasionally, one may want to invoke a special mode called @dfn{integer
-mode}. Normally, in general mode, PSPP will automatically determine
+mode}. Normally, in general mode, PSPP automatically determines
what values occur in the data. In integer mode, the user specifies the
range of values that the data assumes. To invoke this mode, specify the
VARIABLES subcommand, giving a range of data values in parentheses for
each variable to be used on the TABLES subcommand. Data values inside
the range are truncated to the nearest integer, then assigned to that
value. If values occur outside this range, they are discarded. When it
-is present, the VARIABLES subcommand must precede the TABLES subcommand.
+is present, the VARIABLES subcommand must precede the TABLES
+subcommand.
+
+In general mode, numeric and string variables may be specified on
+TABLES. Although long string variables are allowed, only their
+initial short-string parts are used. In integer mode, only numeric
+variables are allowed.
The MISSING subcommand determines the handling of user-missing values.
When set to TABLE, the default, missing values are dropped on a table by
an @samp{M} (for ``missing'') and excluded from statistical
calculations.
-Currently the WRITE subcommand is not used.
+Currently the WRITE subcommand is ignored.
The FORMAT subcommand controls the characteristics of the
crosstabulation tables to be displayed. It has a number of possible
Fixes for any of these deficiencies would be welcomed.
+@node T-TEST, , CROSSTABS, Statistics
+@comment node-name, next, previous, up
+
+@section T-TEST
+
+@display
+T-TEST
+ /MISSING=@{ANALYSIS,LISTWISE@} @{EXCLUDE,INCLUDE@}
+ /CRITERIA=CIN(confidence)
+
+
+(One Sample mode.)
+ TESTVAL=test_value
+ /VARIABLES=var_list
+
+
+(Independent Samples mode.)
+ GROUPS=var(value1 [, value2])
+ /VARIABLES=var_list
+
+
+(Paired Samples mode.)
+ PAIRS=var_list [WITH var_list [(PAIRED)] ]
+
+@end display
+
+
+The @cmd{T-TEST} procedure outputs tables used in testing hypotheses about
+means.
+It operates in one of three modes:
+@itemize
+@item One Sample mode.
+@item Independent Groups mode.
+@item Paired mode.
+@end itemize
+
+@noindent
+Each of these modes are described in more detail below.
+There are two optional subcommands which are common to all modes.
+
+The @cmd{/CRITERIA} subcommand tells PSPP the confidence interval used
+in the tests. The default value is 0.95.
+
+
+The @cmd{MISSING} subcommand determines the handling of missing
+variables.
+If INCLUDE is set, then user-missing values are included in the
+calculations.
+If EXCLUDE is set, which is the default, user-missing
+values are excluded.
+If 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.
+If ANALYSIS is set, then cases are excluded only where a value used in
+the analysis has a system-missing or, if INCLUDE is set, user-missing value.
+
+
+@menu
+* One Sample Mode:: Testing against a hypothesised mean
+* Independent Samples Mode:: Testing two independent groups for the same mean
+* Paired Samples Mode:: Testing two interdependet groups for the same mean
+@end menu
+
+@node One Sample Mode, Independent Samples Mode, T-TEST, T-TEST
+@comment node-name, next, previous, up
+
+@subsection One Sample Mode
+
+The @cmd{TESTVAL} subcommand invokes the One Sample mode.
+This mode is used to test a population mean against a hypothesised
+mean.
+The value given to the @cmd{TESTVAL} subcommand is the value against
+which you wish to test.
+In this mode, you must also use the @cmd{/VARIABLES} subcommand to
+tell PSPP which variables you wish to test.
+
+@node Independent Samples Mode, Paired Samples Mode, One Sample Mode, T-TEST
+@comment node-name, next, previous, up
+@subsection Independent Samples Mode
+
+The @cmd{GROUPS} subcommand invokes Independent Samples mode or
+`Groups' mode.
+This mode is used to test whether two groups of values have the
+same population mean.
+The variable given in the @cmd{GROUPS} subcommand is the independent
+variable which determines to which group the samples belong.
+The values in parentheses are the specific values of the independent
+variable for each group.
+In this mode, you must also use the @cmd{/VARIABLES} subcommand to
+tell PSPP the dependent variables you wish to test.
+
+@node Paired Samples Mode, , Independent Samples Mode, T-TEST
+@comment node-name, next, previous, up
+@subsection Paired Samples Mode
+
+The @cmd{PAIRS} subcommand introduces Paired Samples mode.
+Use this mode when repeated measures have been taken from the same
+samples.
+If the the @code{WITH} keyword is omitted, then tables for all
+combinations of variables given in the @cmd{PAIRS} subcommand are
+generated.
+If the @code{WITH} keyword is given, and the @code{(PAIRED)} keyword
+is also given, then the number of variables preceding @code{WITH}
+must be the same as the number following it.
+In this case, tables for each respective pair of variables are
+generated.
+In the event that the @code{WITH} keyword is given, but the
+@code{(PAIRED)} keyword is omitted, then tables for each combination
+of variable preceding @code{WITH} against variable following
+@code{WITH} are generated.
+
+
@node Utilities, Not Implemented, Statistics, Top
@chapter Utilities
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