Thank you for your interest in the ALSCAL Multidimensional
Scaling program developed here at the L. L. Thurstone Psychometric
Laboratory by Prof. Forrest W. Young.
ALSCAL is available from us as a stand-alone program
for machines with a FORTRAN compiler. ALSCAL is also distributed
as part of the SPSS system. The SAS ALSCAL procedure has been
superseded by the SAS MDS procedure available from SAS Institute, Inc. in the SAS-Stat addon to the
basic SAS system.
Prof. Young's on-line material
about MDS includes
- Prof. Young's books
Young's Monographs on MDS
to Prof. Young's Papers about MDS
Notes for Prof. Young's Graduate Level course on MDS
Summary of ALSCAL's features:
ALSCAL performs metric or nonmetric Multidimensional Scaling
and Unfolding with individual differences options. It can analyze
one or more matrices of dissimilarity or similarity data. The
analysis represents the rows and columns of the data matrix
as points in a Euclidean space. If a row and column are similar,
then their points are close together, while if the row and column
are dissimilar, they are far apart.
- ALSCAL performs metric and nonmetric
analyses: The multidimensional scaling can be
"metric" or "nonmetric". Metric scaling assumes that the
dis/similarity data are quantitative -- that they are measured
at the interval or ratio levels of measurement. Nonmetric
scaling assumes that the data are qualitative -- that they
are at the ordinal level of measurement.
- ALSCAL analyzes one or more
dissimilarity matrices: ALSCAL can analyze one
or more matrices of dis/similarity data. The matrices may
be rectangular or square, symmetric or asymmetric, conditional
or unconditional, and may have missing elements. The program
permits the analysis of any number of matrices, each having
any number of rows or columns.
- ALSCAL does Scaling and Unfolding:
ALSCAL can analyze data whose rows and columns refer to
the same set of objects or events (square data, which may
be symmetric or asymmetric), or which refer to two different
sets of objects or events (rectangular data). When the data
are square the program performs multidimensional scaling,
constructing a Euclidean space which has points in it for
every object/event. When the data are rectangular the program
performs multidimensional unfolding, constructing a Euclidean
space which has points in it for every row and column object/event.
In both cases, the distance between the points corresponding
to the dis/similarity between the objects/events.
- ALSCAL does Individual Differences
Models: ALSCAL can analyze data that are contained
in several matrices. With several matrices ALSCAL can perform
replicated or individual differences multidimensional scaling
or unfolding. For replicated scaling or unfolding the analysis
constructs a Euclidean space just as when there is only
one matrix of data. For individual differences (weighted)
scaling or unfolding, the objects/events are represented
by points in a Euclidean space (as above), while the matrices
are represented by vectors of weights in an additional individual
differences space. The replicated and weighted multidimensional
scaling and unfolding analyses may be either metric or nonmetric.
- Availability: ALSCAL
is available as an IBM-PC (and compatible) executable. It
requires a math-coprocessor. The FORTRAN source code, executable,
test data and example output are distributed on IBM-PC diskettes,
along with a user guide. The source code can be compiled
on other machines. ALSCAL is available within SAS, SPSS
A zip file of
ALSCAL can be obtained by clicking here
The zip file includes
- ALSCAL.EXE, the version for IBM-compatible PCs under DOS.
- ALSCAL84-1.0.sea, the Macintosh version.
- FORTRAN source code of ALSCAL. If you have a FORTRAN compiler,
this code can be compiled to run on other machines.
- Test Data.
Usage: Enter 'ALSCAL' to start ALSCAL. The program then prompts
you to enter the name of the input file and the output file.
When the input filename is not specified, the program stops.
When the output filename is not given, the program chooses the
name 'ALSCAL.OUT'. An END-card causes the program to stop further
reading of the input file. Thus remarks after the END-card will
not cause an error message.
Getting the Documentation:
Young, F.W. & Lewyckyj, R.
- ALSCAL Users
The ALSCAL User's Guide
This monograph presents a complete overview of
how to use ALSCAL, including the SAS, stand-along mainframe
and PC versions. Included is a detailed guide to the command
language for each version, including a summary of 19 common
types of analyses. The monograph also presents comments on
unique aspects of ALSCAL's output, including descriptions
of the individual differences indices and fit indices. In
addition, extensive annotated examples of the input to and
output from ALSCAL are presented, including figures published
from the examples. These examples cover metric MDS, nonmetric
MDS, unfolding, and individual difference scaling. Finally,
a list of all diagnostics, including a full explanation of
each, is presented.
: The ALSCAL Users
Guide can be ordered for $5.00 plus the appropriate mailing
- Add $5.00 for mailing within USA & Canada
- Add $10.00 for mailing to Mexico
- Add $15.00 for mailing outside of North America.
To order, please E-mail
me your name, address and telephone number, telling me you are
ordering ALSCAL documentation. In addition, mail
same information, plus your check or international postal order,
Forrest W. Young
UNC Psychometric Laboratory
CB-3270 Davie Hall
Chapel Hill NC 27599-3270 USA.
The check or international postal order should be made payable
to "UNC Psychometric Laboratory" (or "Forrest Young", if necessary).
Please pay in US dollars only.