Codebooks are useful for documenting essential information about a research project, such as a survey.
A codebook does not have to be a physical book, it is usually a pdf file, but could also be something as simple as a plain text file stored with the quantitative data on a shared drive.
Six important things to include in the codebook for a quantitative research project are discussed in the video below.
- Variable name or label
- A descriptive variable name or label with each shortened, abbreviated code name for that variable for each one in the data set
- Type of variable
- Is the variable a number, a date, a percentage, words, etc.?
- Which question the variable goes with
- Including both the question number and the actual question can be very helpful.
- Which column number(s) it is/are in the data set
- This helps locate it in the structure of the data set
- How missing data or incomplete data are coded in the data set
- For example, is a numerical code such as 999 used to indicate a missing value or is it written out in words ” missing data”?
- Any additional info relevant to your data that would help someone who is analyzing it to better understand it.
- An example of additional information to include would be including the frequency of values as a percentage and a weighted percentage when applicable.
An example of a detailed codebook that includes these important factors is the codebook for the Behavioral Risk Factor and Surveillance Survey (BRFSS), found at https://www.cdc.gov/BRFSS/Annual_data/annual_2019.html
Including these 6 important factors into your codebook helps to improve documentation for the research project for future reference as well as improve the efficiency of the analysis of the data.
Resources for more information on Codebooks:
- SAMHSA. What is a codebook? https://www.datafiles.samsha.gov/faq/what-codebook-nid3440
- Belisle, P and Joseph, L. Codebook Cookbook. Department of Clinical Epidemiology at McGill University Health Centre. http://www.medicine.mcgill.ca/epidemiology/joseph/pbelissle/codebookcookbook/codebookcookbook.pdf