SPSS Dictionary

It's not informative that "a respondent has 0 on v1" unless you know what v1 and 0 refer to. Such information - what the data actually represent - is collectively know as the dictionary.

This tutorial merely explains what the SPSS dictionary is. For learning how to modify it properly (that is, by syntax), see Changing Variable Properties 1 - Introduction.

SPSS Dictionary - What is it?

• The SPSS Dictionary is a part of an SPSS data file that holds all metadata. Literally, metadata is "data about the data".
• Metadata describes the real-world meaning of values, variables and files. The best known properties of the SPSS dictionary are probably variable labels and value labels.
• Don't overlook the importance of such information. In many cases, data are worthless in the absence of correct metadata.
• The dictionary also holds more technical information on variables such as variable types and formats.

SPSS Dictionary Commands

• Some commands refer directly to SPSS' dictionary. An important one is DISPLAY DICTIONARY. which is extensively used by Create Dictionary Dataset.
• Another example is APPLY DICTIONARY - which is basically what SPSS Clone Variables Tool does.
• Commands for modifying variable properties also apply to the SPSS dictionary (instead of the actual data). For a handy overview, see our SPSS Dictionary Tutorials.

SPSS Dictionary - Complete Overview

Note: we tried to sort these properties from most to least important. "Optional" indicates whether a property can (technically) be absent.

SPSS – How to Set Missing Values from Syntax?

Introduction & Practice Data File

When working with SPSS, specifying missing values correctly is often an essential step in analyzing data. This tutorial demonstrates how to set missing values the right way.

Setting Missing Values in SPSS

• Perhaps unsurprisingly, missing values can be specified with the MISSING VALUES command.
• A thing to note, however, is that missing values can be specified for multiple variables at once.
• Second, missing values may be specified as a range. If a range is used, a single discrete missing value can be added to it.
• The syntax example below gives some examples of this.

SPSS Missing Values Syntax Examples

(The test data used by the syntax below are found here.)

Changing Columns in SPSS

• Columns refers to how wide a variable column is displayed on screen. It can be set by the VARIABLE WIDTH command.
• This may be confusing since this does not refer to the "width" (length) of a variable as explained under variable width.
• Although setting columns doesn't affect your actual data, it's of minor importance. For the sake of completeness, the syntax example below demonstrates the command.

SPSS Variable Width Syntax Example

(The test data used by the syntax below are found here.)

Changing Variable Alignment in SPSS

• Variable alignment refers to how data values are aligned within their columns. The options are "left", "centered" or "right".
• As in MS Excel, the default settings are left for string variables and right for numeric variables.
• These can be overridden by the VARIABLE ALIGNMENT command as demonstrated below.

SPSS Variable Align Syntax Example

(The test data used by the syntax below are found here.)

Changing Measurement Levels in SPSS

• On a personal note, we feel the Measure property for setting measurement levels is rather useless. This is something that users - not software - should be aware of and take into account when analyzing data.
• Regretfully, some commands (most notably CTABLES) are actually affected by the measurement levels as specified by the user.
• In this case, the VARIABLE LEVEL command can be used for setting them to nominal, ordinal or scale (for metric variables).

SPSS Variable Level Syntax Example

(The test data used by the syntax below are found here.)

Changing Roles in SPSS

• Just as with Measure, we feel the "Role" property is rather useless and had perhaps better be removed from SPSS.
• For the sake of completeness, it can be modified as demonstrated below.

SPSS Variable Role Syntax Example

(The test data used by the syntax below are found here.)

SPSS – Set Variable Labels with Syntax

Managing variable and value labels without syntax is way more work than necessary. This tutorial explains how to do this more efficiently.

Changing Variable Labels in SPSS

• As with other parts of the dictionary, there's no "Paste" option for modifying variable labels.
• Be aware that manual modifications - apart from being time consuming - are not recorded in the journal file. The way to go here is using syntax.
• Changing or adding variable labels is straightforward using the VARIABLE LABELS command.
• Although not always necessary, it is recommended to always use quotes around the label text.
• If more than one variable is labelled in a single command, use slashes (/) to separate specifications.

SPSS Variable Labels Syntax Examples

(The test data used by the syntax below are found here.)

Changing Value Labels in SPSS

• The VALUE LABELS command should be used carefully since it will first erase all value labels for a variable and then apply whatever you specify. This often made mistake is demonstrated in the syntax below.
• Often, ADD VALUE LABELS is a better alternative for changing or adding value labels.
• Note that both commands can be applied to multiple variables simultaneously. This may save a lot of time when combined with TO and ALL keywords.
• Note that the value labels themselves should be quoted. If there's a single quote in a label, you need to escape it by doubling it. Alternatively, double quotes can be used around a labels containing single quotes.

SPSS Value Labels Syntax Examples

(The test data used by the syntax below are found here.)

Changing Variable Properties 4 – Width and Decimals

Changing a variable's width is rarely necessary. Nevertheless, it's good to know how when it's needed and how it's done.

Changing Variable Width in SPSS

• For string variables, width refers to how many characters a value can hold. An exception are multibyte characters as explained in SPSS Unicode Mode.
• Somewhat confusingly, "width" is not the width of a variable's column as displayed on screen, which is referred to as columns.
• For string variables, width should be increased when new values are desired that are longer than the current width. This is demonstrated by the syntax example below.
• For numeric variables, "width" refers to how many digits should be displayed. However, SPSS will often override the specified width is it's insufficient. If not, FORMATS can be used for increasing it.

SPSS Formats and Alter Type Syntax Examples

(The test data used by the syntax below are found here.)

Changing Decimal Places in SPSS

• Decimal places can be changed by the FORMATS command. Just note that the first number refers to the width of the entire variable (including decimals) so the second number (decimals) should always be smaller.
• Also, keep in mind that the actual data values will not change because of using FORMATS. They are merely displayed differently.

SPSS Formats Syntax Example

(The test data used by the syntax below are found here.)

Changing Variable Properties 3 – Type

SPSS offers several ways to change a variable's type. This tutorial will walk you through some examples.

SPSS Variable Type - Why Change it in the First Place?

• What you can do with a variable may depend on its type and - to a lesser extent - on its format.
• For example, you can extract substrings from string variables but not from numeric variables.
• For time calculations ("how many hours between ...") you'll want to use proper time variables and/or date variables.
• In some cases, you may want to use such operations on a variable that are not possible with its current type or format. In such cases, changing these is often the way to go.

Changing Variable Type in SPSS

• First note that there's really only two variable types in SPSS: string and numeric. For more on this, see SPSS Numeric Variables Basics.
• Starting from SPSS version 16, one can use ALTER TYPE in order to change a variable's type. Keep in mind that it overwrites the original variable and results in system missing values if it can't apply the requested conversion.
• However, loss of data or effort can be prevented here by working from syntax and making proper backups.
• Alternatively, use SPSS Clone Variables Tool before applying ALTER TYPE.

SPSS Alter Type Syntax Examples

(The test data used by the syntax below are found here.)

SPSS String and Numeric Functions

• An alternative and more classical way for converting numeric variables into strings is with the STRING function.
• Note that new string variables (in contrast to numeric variables) first have to be declared ("created") by the STRING command.
• Converting string variables to numeric is done with the NUMERIC function.

SPSS String and Numeric Syntax Examples

(The test data used by the syntax below are found here.)

SPSS Autorecode Command and Valuelabels Function

• Last but not least, string variables can be converted to numeric variables by the AUTORECODE command.
• Every distinct string value is rendered as the value label of a value in a new numeric variable.
• AUTORECODE is usually applied to string variables with many duplicate values.
• The reverse, passing value labels as values into a new string variable is done by the VALUELABELS function.
• Before using it, the new string variable must first be declared with the STRING command.

SPSS Autorecode and Valuelabels Syntax Examples

(The test data used by the syntax below are found here.)

Changing Variable Properties 2 – Names

The right way for changing variable names in SPSS is using RENAME VARIABLES. Changing variable names manually in variable view is a bad idea because you can't keep track of what you did. This tutorial shows a better alternative.

Changing Variable Names in SPSS

• Changing variable names with syntax is straightforward with the RENAME VARIABLES command.
• The main thing to keep in mind is that you should use parentheses when you rename more than one variable at once.
• Second, make sure that renaming variables does not result in duplicate variable names.
• Existing variable names may be used as new variable names if they're renamed themselves within the same command. So for instance, RENAME (v1 v2 = v2 v1). will work.

SPSS Rename Variables Syntax Examples

(The test data used by the syntax below are found here.)

Changing Variable Properties 1 – Introduction

A great way to start working from syntax is using "Paste" instead of "Ok". However, there's no "Paste" option for modifying most variable properties. This tutorial shows how handle that properly.

Changing Variable Properties

• Note that all variable properties (such as variable labels and value labels) are part of the SPSS dictionary.
• It is strongly recommended you use syntax in order to modify these. Why this is so important is explained in SPSS Syntax - Six Reasons you Should Use it.
• You can't "Paste" this syntax from any menu but fortunately it's very straightforward.
• This tutorial starts with creating some test data for practicing and then walks through each variable property.
• It's recommended you follow along and copy-paste-run all syntax. Don't forget to inspect your variable view after each step.

Creating Test Data

Click on of the Properties in the Screenshot Below

Overview Changing Variable Properties

1. Changing Variable Names in SPSS
2. Changing Variable Type in SPSS
3. Changing Variable Width in SPSS
4. Changing Variable Decimals in SPSS
5. Changing Variable Labels in SPSS
6. Changing Value Labels in SPSS
7. Setting Missing Values in SPSS
8. Changing Columns in SPSS
9. Changing Variable Alignment in SPSS
10. Changing Variable Measure in SPSS
11. Changing Variable Role in SPSS