Final answer:
Dr. Thatcher is coding the interview responses for research purposes to analyze the qualitative data collected from new parents and understand common challenges faced during early parenthood.
Step-by-step explanation:
Dr. Thatcher is coding this interview for its research purposes. The process of organizing and categorizing the interview responses into themes such as "sleep/exhaustion", "understanding baby's cues", and "emotional volatility" helps Dr. Thatcher to systematically analyze the qualitative data collected from new parents. This data analysis technique is a standard method in psychological and sociological studies to understand complex human behaviors and challenges, in this case, those related to new parenthood.