SPSS® 12.0 Command Syntax Reference

ERRORBAR Subcommand
IGRAPH 761
Error bars help you to visualize distributions and dispersion by indicating the variability of
the measure being displayed. The mean of a scale variable is plotted for a set of categories,
and the length of an error bar on either side of the mean value indicates a confidence interval
or a specified number of standard errors or standard deviations. Error bars can extend in one
direction or in both directions from the mean. Error bars are sometimes displayed in the same
chart with other chart elements, such as bars.
One of the following three keywords indicating the statistic and percentage/multiplier
applied to the error bars must be specified:
CI(Pct) Error bars represent confidence intervals. Pct indicates the level of confidence
and varies from 0 to 100.
SD(sdval) Error bars represent standard deviations. Sdval indicates how many standard
deviations above and below the mean the error bars extend. Sdval must
between 0 and 6.
SE(seval) Error bars represent standard errors. Seval indicates how many standard errors
above and below the mean the error bars extend. Seval must between 0
and 6.
In addition, the following keywords can be specified:
LABEL Labels error bars with means (VAL) and the number of cases (N).
DIRECTION Error bars can extend both above and below the mean values (BOTH),
only above the mean values (UP), only below the mean values
(DOWN), or above for error bars above the baseline and below for
error bars below the baseline (SIGN).
CAPSTYLE For error bars, the style can be T-shaped (T), no cap (NONE), or a cap
with end pieces (FANCY). The default style is T-shaped.
SYMBOL Displays the mean marker (ON). For no symbol, specify OFF.
BASELINE val Defines the value (val) above which the error bars extend above the
bars and below which the error bars extend below the bars.
CAPWIDTH(pct) Controls the width of the cap relative to the distance between
categories. Pct equals the percent of the distance. The default value for
pct is 45.
Example
IGRAPH
/X1=VAR(volume94) TYPE=CATEGORICAL
/Y=VAR(sales96) TYPE=SCALE
/BAR (MEAN) LABEL INSIDE VAL SHAPE=RECTANGLE BASELINE=0.00
/ERRORBAR SE(2.0) DIRECTION=BOTH CAPWIDTH (45) CAPSTYLE=FANCY.
• BAR creates a bar chart with rectangular bars. The bars represent the mean sales96 values
for the volume94 categories.
• ERRORBAR adds error bars to the bar chart. The error bars extend two standard errors
above and below the mean.