One of the feedback I received after my PhD interview failure was that " there is not enough evidence of ability to operationalize the research". So how can I clarify my capability of carrying out a research for my next interview. During my failed interview, I was ask to talk about my prior research, therefore I mentioned my master thesis used SPSS. However it seems that my response was not compelling enough.
Mentioning your skills with SPSS is great but statistical analysis is just a part of research. (And if we speak about this part, I would be more interested in which statistical methods you used and why (who selected these methods, you or your supervisor?, did you consider other methods?, etc.) to see how well you understand statistical analyses.)
More relevant would be your research question, design and contribution to the whole process (Did you come up with these on your own or was it given to you? What was your contribution in designing the study? Did you collect the data? Did you apply for ethical permission (if applicable) on your own? Do you plan to publish your thesis?)
If you are asked a similar question at the next interview, try to give a brief summary of your thesis (topic, design, methods, results, your contribution).
Also: please do not be discouraged that you have not been selected this time! Being invited for an interview means that you are a good candidate. It is just that there are many good candidates out there and limited number of places. Learn from this experience, do not give up and good luck with the next interview!
One of the best ways to demonstrate skills and ability to carry out a research project is to ask intelligent and relevant questions about the project as part of your interview. When I interview students, that is one of the ways I find out about their ability to understand and put new information in context.
So for instance, a student who will be running experiments might ask about current protocols related to lab work during COVID and then discuss how they might make sure to get the work done under those conditions. Someone doing data analysis might ask about the structure of the data to be analyzed and the packages or libraries used most by the group. They might then comment on how they would approach the analysis or other packages they have found helpful for similar data.
When you treat the interview as a collaborative conversation you can most easily demonstrate your ability to carry out the work successfully.