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ONEWAY [/VARIABLES = ] var_list BY var /MISSING={ANALYSIS,LISTWISE} {EXCLUDE,INCLUDE} /CONTRAST= value1 [, value2] ... [,valueN] /STATISTICS={DESCRIPTIVES,HOMOGENEITY} /POSTHOC={BONFERRONI, GH, LSD, SCHEFFE, SIDAK, TUKEY, ALPHA ([value])}
The ONEWAY
procedure performs a one-way analysis of variance of
variables factored by a single independent variable.
It is used to compare the means of a population
divided into more than two groups.
The dependent variables to be analysed should be given in the VARIABLES
subcommand.
The list of variables must be followed by the BY
keyword and
the name of the independent (or factor) variable.
You can use the STATISTICS
subcommand to tell PSPP to display
ancilliary information. The options accepted are:
The CONTRAST
subcommand is used when you anticipate certain
differences between the groups.
The subcommand must be followed by a list of numerals which are the
coefficients of the groups to be tested.
The number of coefficients must correspond to the number of distinct
groups (or values of the independent variable).
If the total sum of the coefficients are not zero, then PSPP will
display a warning, but will proceed with the analysis.
The CONTRAST
subcommand may be given up to 10 times in order
to specify different contrast tests.
The MISSING
subcommand defines how missing values are handled.
If LISTWISE
is specified then cases which have missing values for
the independent variable or any dependent variable will be ignored.
If ANALYSIS
is specified, then cases will be ignored if the independent
variable is missing or if the dependent variable currently being
analysed is missing. The default is ANALYSIS
.
A setting of EXCLUDE
means that variables whose values are
user-missing are to be excluded from the analysis. A setting of
INCLUDE
means they are to be included. The default is EXCLUDE
.
Using the POSTHOC
subcommand you can perform multiple
pairwise comparisons on the data. The following comparison methods
are available:
LSD
Least Significant Difference.
TUKEY
Tukey Honestly Significant Difference.
BONFERRONI
Bonferroni test.
SCHEFFE
Scheffé’s test.
SIDAK
Sidak test.
GH
The Games-Howell test.
The optional syntax ALPHA(value)
is used to indicate
that value should be used as the
confidence level for which the posthoc tests will be performed.
The default is 0.05.
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