It is widely accepted that meaningful variable names are important for comprehension. We conducted a controlled experiment in which 9 professional developers try to understand 6 methods from production util classes, either with the original variable names or with names replaced by meaningless single letters. Results show that parameter names are more significant for comprehension than local variables. But, surprisingly, we also found that in 3 of the methods there were no significant differences between the control and experimental groups, due to poor and even misleading variable names. These disturbingly common bad names reflect the subjective nature of naming, and highlight the need for additional research on how variable names are interpreted and how better names can be chosen

1. Effects of
Variable Names
on
Comprehension
An Empirical Study
Eran Avidan & Dror G Feitelson

2. Meaningful identifier names are important to comprehension

3. Full word identifiers lead to better comprehension
than identifiers composed of single letters

4. Well...not always

5. Empirical study

6. Research questions
What impact do identifier names have on the comprehension of what a
method does?
Which type of identifiers contribute more to comprehension, parameters or
local variables?

7. Controlled Experiment
8 Professional developers
6 Methods from popular open source utility packages
38 Sessions
22 Hours

8. The idea

9. The Results

10. Meaningful names lead to faster time to comprehension

11. Clear separation in time to comprehension

12. Time to comprehension

13. Bad names can mislead just as much as Good names inform

14. Misleading names (or types) are worse than meaningless
names like consecutive letters of the alphabet

15. Misleading how?

16. Use of names that are too abstract
Uncommon use of variable types
Use of synonyms
The apparent functionality does not make sense

17. Naming is subjective

18. In spontaneous word choice
Two people favor the same term with a probability of less than 0.2
The vocabulary problem in human-system communication

19. Parameters vs Locals

20. Parameters contribute more to comprehension

21. Our contributions to the field
Quantify the effect of meaningful names in an experimentally valid manner
Show that naming is subjective, and bad names are not uncommon
Identify parameters as more important than local variables
Demonstrate the use of experiments with dynamic treatments

22. exit(0)