Produces a simple stem-and-leaf chart (J. Ollerton & S.A. Harding).
No options
Parameters
DATA = variates |
Data values for each plot |
|---|---|
NDIGITS = scalars |
Number of digits in the leaves of each plot |
STEMUNITS = scalars |
Scale units for the stem values in each plot |
Description
STEM produces a simple stem-and-leaf chart of a variate of data. The stems indicate leading digits and the leaves indicate subsequent digits. By default, the leaves are formed from single digits; the parameter NDIGITS can be used to specify the number of digits in each leaf if more than one is required. The STEMUNITS parameter can be used to specify the units represented by the stem values. By default, this is determined from the data so that the display will fit within a single screen or page of output. Small values of STEMUNITS (in comparison to the range of the data) should be avoided as they may generate far too many lines of output. The display produced by STEM is restricted to the current output width; any lines that have to be truncated at the right-hand margin are terminated by >, indicating their continuation.
Options: none. Parameters: DATA, NDIGITS, STEMUNITS.
Method
The variate of data is scaled appropriately and printed into a text. Using CONCATENATE the individual stem and leaf digits are extracted and then formed into another text structure which is printed out as the stem-and-leaf display. Missing values are excluded from the data.
Action with RESTRICT
STEM takes account of any restriction on the data variate.
Reference
Tukey, J.W. (1977). Exploratory Data Analysis. Addison-Wesley.
See also
Directive: DHISTOGRAM.
Procedures: BOXPLOT, DOTPLOT, RUGPLOT.
Commands for: Graphics.
Example
CAPTION 'STEM example'; STYLE=meta VARIATE [NVALUES=18] Prices READ [PRINT=errors] Prices 250 150 795 895 696 1699 1499 1099 1693 1166 688 1333 895 1775 895 1895 795 806 : PRINT [ORIENT=across] Prices; DECIMALS=0 STEM Prices; NDIGIT=1 STEM Prices; NDIGIT=2