Working with string variables in SPSS is pretty straightforward if one masters some basic string functions. This tutorial will quickly walk you through the important ones.

SPSS Main String Functions

• CHAR.SUBSTR (substring) - Extract character(s) from string
• CONCAT (concatenate) - Combine strings
• CHAR.INDEX - Find first occurrence of character(s) in string
• CHAR.RINDEX (right index) - Find last occurrence of character(s) in string
• REPLACE - Replace character(s) in string by different one(s)
• CHAR.LENGTH - Return number of characters in string
• LTRIM (left trim) - Remove leading spaces (or, rarely, other characters)
• RTRIM (right trim) - Remove right trailing spaces (or, rarely, other characters)
• LOWER (lower case) - Convert all letters to lower case
• UPCASE (upper case) - Convert all letters to upper case

SPSS Syntax Example

We asked respondents to type in their first name, surname prefix and last name. We'd like to combine these into full names and correct some irregularities such as incorrect casing and double spaces. For creating some test data, close all open datasets and run the syntax below.

1. Correcting First Names

• One approach is to first correct each name component separately and then combine them.
• For the data at hand, first names should start with a capital and remaining letters should be in lower case.
• We'll break things up in small steps. We'll gradually combine these using substitution: using functions within functions.
• It's recommended you inspect the results carefully after running each step.
• Note there's separate tutorials on substrings and concatenate.

2. Correcting Surname Prefixes

• Since these are Dutch names, surname prefixes should be entirely in lower case.
• However, we'll first remove any leading spaces using the LTRIM function.
• Next we'll replace double by single spaces. For correcting longer sequences of spaces, see the second syntax example of SPSS LOOP Command.

3. Combining First and Last Names

• For last names, the same rules hold as for first names: the first letter in upper case and remaining letters in lower case.
• Therefore, we can reuse the expression we wrote for the first names after some minor modifications.
• Now, combining first, middle and last names requires slightly more than a basic concatenation. This is because SPSS automatically right pads string values with spaces to match the length of the string variable.
• Therefore, concatenating 3 strings with length 20 results in a string with length 60. In case of insufficient variable width, only the first characters are shown. This is what happens in the example below (although it looks like the concatenation is not working).
• In Unicode mode RTRIM is applied automatically. However, including it in the syntax anyway ensures that things will work properly regardless whether or not SPSS is in Unicode mode or not.

4. Flag Single Letter Names

• Unfortunately, not all respondents filled out their real names. Many of such cases can't be detected from the data at hand but some suspicious patterns are easily identified.
• One such pattern are very short (1 or 2 letter) first or last names. Since we have those separately in the data we can use CHAR.LENGTH to flag these cases.
• For combined names, the first name consists of all letters up to the first space. We can find it by using the CHAR.INDEX function.
• Reversely, the last name holds all letters after the last space which can be found by CHAR.RINDEX. Subtracting the position of the last space from the length of the name returns the length of the last name.
• For example, "Anneke van den Berg" are 19 letters. The last space is the 15^th letter. Now 19 minus 15 returns 4 - which is indeed the length of "Berg".