Presented at the 22nd European congress of work and organizational psychology (EAWOP 2025)
Interest congruence, the alignment between an individual's vocational interests and their occupational environment, is a key concept in vocational psychology and career counseling. Various operationalizations of interest congruence have been proposed, with profile-based measures (e.g., profile correlations) showing better predictive value for career outcomes. However, researchers often lack full interest profiles and instead rely on three letter Holland codes derived from interest inventories, occupational data, or educational qualifications coded through systems like the Strong Interest Inventory (SII) or O*NET. In these cases, top-letter-oriented approaches, such as the C-index (Brown & Gore, 1994), are used to calculate congruence based on the three most dominant interest types. Eggerth and Andrew (2006) proposed a modified C-index that allows comparisons between Holland codes of unequal lengths, enhancing its applicability.
While the R package holland (Heine et al., 2021) facilitates computation of the C-index, it currently supports only three-letter Holland codes. To address this limitation, we developed an open-source R code that computes Eggerth and Andrew’s modified C-index for Holland codes of varying lengths (1-3 letters). This user-friendly tool processes congruence calculations and outputs results in an Excel-compatible format, streamlining analysis for researchers and practitioners.
The modified C-index has been underutilized in the literature, with most studies favoring the original C-index. Preliminary research on limited samples suggests that the modified C-index produces similar or slightly higher congruence values compared to the standard version. However, further validation across diverse cultures and larger datasets is necessary to establish its utility.
This contribution provides a practical tool for computing the modified C-index, enabling researchers to apply and validate Eggerth and Andrew’s (2006) work more efficiently. By facilitating broader adoption of the modified index, this code supports advancements in interest congruence research and its applications in vocational psychology.
Requirements:
- R >= 4.0.0
- dplyr
- openxlsx
- here
Install the packages using:
install.packages(c("dplyr", "openxlsx", "here"))There is an example worksheet in the data directory. You can add your own data, just make sure to change the following lines of code inside the script.r file:
filename <- here("data", "example.xlsx") # your data filename
input_sheet <- "data" # your input data worksheet
output_sheet <- "results" # your results worksheet Position yourself inside the project directory and run the script:
source("script.r")You can also run the script from RStudio if you prefer.
| Role | Name | Website |
|---|---|---|
| Corresponding Author | Katarina Banov Trošelj | 🌐 Personal Website |
| Co-author | Marina Banov | 🌐 Personal Website |