The Art of Coding Variables and Creating Codebooks and Databases for Statistical Analysis

1. The Art of Coding Variables and Creating Codebooks and Databases for Statistical Analysis Survey of Statistical Methods Friday, January 21, 2005

2. What is a Data Codebook? Contents of a Data Codebook • A blank copy of each of your ‘data forms’ • A copy of your data form with the variable names noted on it • A copy of your ‘data coding system’ that summarizes the properties of your variables • A copy of your data (printed after all data is entered)

3. Steps for Data Coding • Collect all data on a “data form”. All data for a subject should be centralized • Create a subject ID system and write ID on each form for every subject • Write variable names on a blank ‘data form’ • Create a coding summary in Word or EXCEL • Create database in SPSS

4. Data ‘Forms’ Create an ID numbering system. Write variable names on a blank questionnaire. Create Codebook in Word or EXCEL

5. Information that must be in your coding sheet • Variable name (**** see ‘rules’ for naming variables) • Type of variable (number or text.. if text, max size) • Short description (called Variable Label) • Unit of measure • Value labels (if variable is categorical) • Minimum and maximum values • Designating ‘missing values’ (when appropriate)

6. Rules for Creating Variable Names • Maximum of 8 characters with no spaces. • The name must begin with a letter. The remaining characters can be any letter, any digit, a period, or the symbols @, #, _, or $. • Can not end with a period or an underscore (_). • Can not use special characters(e.g., !, ?, ’, and *) • Each variable name must be unique; duplication is not allowed. Variable names arenot case sensitive. The names NEWVAR, NewVar, and newvar are all considered identical.

8. Creating a database in SPSS • SPSS = “Statistical Package for the Social Sciences” • Open SPSS for Windows (do not use xxxx) • Close the initial window that appears (press Cancel)

9. Variable View vs. Data View

11. Entering information for the computer questionnaire

12. Homework for Friday(1/28/05) • Code the variables and create a codebook and database for the “Sample Questionnaire” • You will be handing in your work in the following form… (staple all pages together) • Cover page with your name, assignment title, date, and an appropriate graphic. • Copy of the sample questionnaire with variable names you selected hand written on it. • The “Codebook” (created in WORD or EXCEL). • A screen print of the Variable View worksheet from SPSS containing your database. • A screen print of the Data View worksheet with data for 3 subjects (use your data + data from 2 other people in class).

13. SPSS Help • Variable View Tab • This is where you establish the variable names and enter information from your codebook. • Be sure that your first variable is an IDNO and be sure to number your data sheets. • Data View Tab • This is where you enter the actual numbers from your data sheets. Each row represents one subject.