I read about quasi-experimental design and the variations it has such as pre-test post-test non-equivalent groups, and also experimental designs. Having compared these two, I ascertained that the difference between this variation of quasi-experimental design(pre-test post-test non-equivalent groups) and experimental design is randomization. However, what I couldn't understand was:
Why should quasi-experimental design even exist when we can do randomization easily and the randomization has more benefits than matching the participants?
Honestly, I search for the answer but I couldn't find any, and obviously that is why I'm asking a question, yet if you find any alike question I would be happy if you refer me to it. I genuinely appreciate it if you refer me to at least one resource as well. The reference book for the discrimination between these two designs: Introduction to Research Methods and Data Analysis in Psychology, Third Edition by Darren Langdridge and Gareth Hagger-Johnson