From af028e5549ee13ed298da4822ff5aa674ff62031 Mon Sep 17 00:00:00 2001 From: John Darrington Date: Wed, 18 Jan 2012 20:32:57 +0100 Subject: [PATCH] Added documentation for the MEANS command --- NEWS | 1 + doc/statistics.texi | 143 +++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 141 insertions(+), 3 deletions(-) diff --git a/NEWS b/NEWS index 0faa8ca2..28e3ab58 100644 --- a/NEWS +++ b/NEWS @@ -18,6 +18,7 @@ Changes from 0.6.2 to 0.7.8: - DATASET DISPLAY - DATASET NAME - MATCH FILES + - MEANS - MRSETS - PRESERVE and RESTORE - QUICK CLUSTER diff --git a/doc/statistics.texi b/doc/statistics.texi index bf5ea3a3..edd96d09 100644 --- a/doc/statistics.texi +++ b/doc/statistics.texi @@ -11,6 +11,7 @@ far. * CORRELATIONS:: Correlation tables. * CROSSTABS:: Crosstabulation tables. * FACTOR:: Factor analysis and Principal Components analysis +* MEANS:: Average values and other statistics. * NPAR TESTS:: Nonparametric tests. * T-TEST:: Test hypotheses about means. * ONEWAY:: One way analysis of variance. @@ -634,7 +635,145 @@ 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 MEANS +@section MEANS + +@vindex MEANS +@cindex means + +@display +MEANS [TABLES =] + @{varlist@} + [ BY @{varlist@} [BY @{varlist@} [BY @{varlist@} @dots{} ]]] + + [ /@{varlist@} + [ BY @{varlist@} [BY @{varlist@} [BY @{varlist@} @dots{} ]]] ] + + [/CELLS = [MEAN] [COUNT] [STDDEV] [SEMEAN] [SUM] [MIN] [MAX] [RANGE] + [VARIANCE] [KURT] [SEKURT] + [SKEW] [SESKEW] [FIRST] [LAST] + [HARMONIC] [GEOMETRIC] + [DEFAULT] + [ALL] + [NONE] ] + + [/MISSING = [TABLE] [INCLUDE] [DEPENDENT]] +@end display + +You can use the MEANS command to calculate the arithmetic mean and similar +statistics, either for the dataset as a whole or for categories of data. + +The simplest form of the command is +@example +MEANS @var{v}. +@end example +@noindent which calculates the mean, count and standard deviation for @var{v}. +If you specify a grouping variable, for example +@example +MEANS @var{v} BY @var{g}. +@end example +@noindent then the means, counts and standard deviations for @var{v} after having +been grouped by @var{g} will be calculated. +Instead of the mean, count and standard deviation, you could specify the statistics +in which you are interested: +@example +MEANS @var{x} @var{y} BY @var{g} + /CELLS = HARMONIC SUM MIN. +@end example +This example calculates the harmonic mean, the sum and the minimum values of @var{x} and @var{y} +grouped by @var{g}. + +The CELLS subcommand specifies which statistics to calculate. The available statistics +are: +@itemize +@item MEAN +@cindex arithmetic mean + The arithmetic mean. +@item COUNT + The count of the values. +@item STDDEV + The standard deviation. +@item SEMEAN + The standard error of the mean. +@item SUM + The sum of the values. +@item MIN + The minimum value. +@item MAX + The maximum value. +@item RANGE + The difference between the maximum and minimum values. +@item VARIANCE + The variance. +@item FIRST + The first value in the category. +@item LAST + The last value in the category. +@item SKEW + The skewness. +@item SESKEW + The standard error of the skewness. +@item KURT + The kurtosis +@item SEKURT + The standard error of the kurtosis. +@item HARMONIC +@cindex harmonic mean + The harmonic mean. +@item GEOMETRIC +@cindex geometric mean + The geometric mean. +@end itemize + +In addition, three special keywords are recognized: +@itemize +@item DEFAULT + This is the same as MEAN COUNT STDDEV +@item ALL + All of the above statistics will be calculated. +@item NONE + No statistics will be calculated (only a summary will be shown). +@end itemize + + +More than one @dfn{table} can be specified in a single command. +Each table is separated by a @samp{/}. For +example +@example +MEANS TABLES = + @var{c} @var{d} @var{e} BY @var{x} + /@var{a} @var{b} BY @var{x} @var{y} + /@var{f} BY @var{y} BY @var{z}. +@end example +has three tables (the @samp{TABLE =} is optional). +The first table has three dependent variables @var{c}, @var{d} and @var{e} +and a single categorical variable @var{x}. +The second table has two dependent variables @var{a} and @var{b}, +and two categorical variables @var{x} and @var{y}. +The third table has a single dependent variables @var{f} +and a categorical variable formed by the combination of @var{y} and @var{z}. + + +By default values are omitted from the analysis only if missing values +(either system missing or user missing) +for any of the variables directly involved in their calculation are +encountered. +This behaviour can be modified with the /MISSING subcommand. +Three options are possible: TABLE, INCLUDE and DEPENDENT. + +/MISSING = TABLE causes cases to be dropped if any variable is missing +in the table specification currently being processed, regardless of +whether it is needed to calculate the statistic. + +/MISSING = INCLUDE says that user missing values, either in the dependent +variables or in the categorical variables should be taken at their face +value, and not excluded. + +/MISSING = DEPENDENT says that user missing values, in the dependent +variables should be taken at their face value, however cases which +have user missing values for the categorical variables should be omitted +from the calculation. @node NPAR TESTS @section NPAR TESTS @@ -1452,5 +1591,3 @@ exclude them. Cases are excluded on a listwise basis; if any of the variables in @var{var_list} or if the variable @var{state_var} is missing, then the entire case will be excluded. - - -- 2.30.2