it may contain up to 1000 variables;
for each variable, it contains at minimum the variables number, its type (numeric or alphabetic), and its location in the data record;
for each variable, a variable name, two missing data codes, the number of decimal places and a reference number may also be specified;
for qualitative variables, codes and corresponding labels may be included.

The couple of a dictionary and the data it describes is known as an IDAMS dataset .

IDAMS matrices. Some analysis programs use a square or rectangular matrix of as input rather than a raw data file.

The square matrix is used for symmetric arrays of bivariate statistics with a constant on the diagonal. Only the upper right-hand corner of the matrix is stored, without the diagonal.

The rectangular matrix is for non-symmetric arrays of values. The meaning of the rows and columns varies according to the IDAMS program.

1.6 IDAMS Commands and the ``Setup'' File

Data management and analysis facilities (described in 1.3 and 1.4, except WinIDAMS interactive components) are available in batch components called programs. Execution of an IDAMS program is launched by a "setup" file. This contains specifications such as file definitions, program control statements, variable recoding instructions, etc., separated by IDAMS commands (starting with a $ character) which identify the kind of information being specified. The first IDAMS command in the setup file always identifies the first program to be executed, e.g.


     $RUN TABLES
     $FILES
     DICTIN = name of dictionary file
     DATAIN = name of data file
     $SETUP
         program control statements for TABLES program
     $RECODE
         variable transformation statements

1.7 Standard IDAMS Features

Case selection. By default all cases in a file will be processed in a program execution. To select a subset, a filter statement is included in the setup file, e.g. INCLUDE V3=1 (include only those cases where variable 3 is equal to 1).

Variable selection. Variables are referenced by their variable numbers assigned in the dictionary. A set of variables is specified in a variable list following keywords such as VARS, CONVARS, OUTVARS. Such variable lists may also include R-variables constructed by the IDAMS Recode facility (see below), e.g. VARS=(V3-V6,V129,R100,R101).

Transforming/Recoding data. A powerful Recode facility permits the recoding of variables and the construction of new variables. Recoding instructions are prepared by the user in the IDAMS Recode language. This includes the possibility of arithmetic computation as well as the use of several special functions for operations such as the grouping of values, the creation of "dummy" variables, etc. Conditional statements are also allowed. Examples of Recode statements for constructing 3 new variables R100, R101 and R102 are:


     R100=V4+V5
     R101=BRAC(V10,0-15=1,16-60=2,61-98=3,99=9)
     IF (MDATA(V3,V4) OR V4 EQ 0) THEN V102=99 ELSE R102=V3*100/V4

The R-variables thus constructed for each case can be used temporarily in the program being executed or can be saved in a dataset using the TRANS program.

Weighting data. When complex sampling procedures are used during data collection, it may be necessary to use different weights for cases during analysis. Such weights are usually stored as a variable in the data file. The WEIGHT parameter is then used in the program control statements to invoke weighting, e.g. WEIGHT=V5.

Treatment of missing data and "bad" data. Special values for each numeric variable can be identified as missing data codes and stored in the dictionary. During data processing missing data is handled through two parameters:

MDVALUES (specifies which missing data codes are to be used to check for missing data in numeric variables);
MDHANDLING (specifies what is to be done if missing data are encountered).

Normally it is assumed that data have been cleaned prior to analysis. If this is not the case, then the BADDATA parameter is available for skipping cases with non-numeric values or blanks in numeric fields, or for treating such values as missing data.

1.8 Import and Export of Data

IDAMS does not use special internal file format for storing data. Any fixed format character data file can be described by an IDAMS dictionary and then input to IDAMS. Thus if data from other software can be output into a fixed format text file, then there is no need for a special import function. Tab delimited and comma separated free format data files can be imported directly through the WinIDAMS User Interface. Moreover, the IMPEX program allows a fixed format IDAMS data file to be created from a text file in free or DIF format.

Data files created by IDAMS are always fixed format character files. Such files can be input directly to other software along with the appropriate data descriptive information for that software. Tab delimited and comma separated free format data files can be exported directly through the WinIDAMS User Interface. Moreover, the IMPEX program allows a fixed format IDAMS data file to be exported as a text file in free or DIF format.

IDAMS matrices are stored in a format specific to IDAMS (described in the "Data in IDAMS" chapter). The IMPEX program can be used to import/export free format matrices.

1.9 Exchange of Data Between CDS/ISIS and IDAMS

There is a separate program, WinIDIS, which prepares data description and performs data transfer between IDAMS and CDS/ISIS (the UNESCO software for database management and information retrieval). Such transfer is controlled by IDAMS and ISIS data description files (the IDAMS dictionary and the CDS/ISIS Field Definition Table). When going from ISIS to IDAMS, a new IDAMS dictionary and data files are always constructed and they can be match-merged with other data using IDAMS data management facilities. When going from IDAMS to ISIS, there are three possibilities: (1) a completely new data base can be constructed, (2) transferred records can be added to an existing data base as new data base records, (3) records of an existing data base can be updated with the transferred data.

1.10 Structure of this Manual

All the general features of IDAMS, including the Recode facility, are described in Part 1 of this Manual.

Part 2 includes installation instructions, description of files and folders used in WinIDAMS, a section entitled "Getting Started" which takes a user through the steps required to perform simple task, and description of the WinIDAMS User Interface.

In-depth descriptions of each IDAMS program are given in Parts 3 and 4 . These write-ups contains the following sections:

General Description. A statement of the primary purpose of the program.

Standard IDAMS Features. Statements about the case and variable selection possibilities, data transformation, weighting capabilities, and missing data handling.

Description of "printed" output. Details of results destined to be printed (or reviewed on the screen).

Description of output and input files. One section for each IDAMS dataset, each matrix and each other distinct input or output data file, giving a description of data expected or generated by the program.

Setup Structure. A designation of the file definitions, IDAMS commands, and program control statements needed to execute the program.

Program Control Statements. The parameters and/or formats of each of the program control statements with an example of each type.

Restrictions. A summary of the program limitations.

Examples. Examples of complete sets of control statements for executing the program.

Part 5 provides description of WinIDAMS interactive components for graphical exploration of data, for time series analysis and for construction of multidimensional tables.

Details of statistical techniques, formulas and references for analysis programs can be found in Part 6 .

Finally, errors issued by IDAMS programs are summarized in the Appendix.