I have formulated a sentence for which I am not sure if the word "thematically" is correct. The sentence is the following: "The material was coded analytically (based on the data) and thematically (based on the questions). This means that the answers to each of the three interview questions, which dealt with three relevant but distinct topics, were seen as three data sets." What I want to say with "thematically" is that the material was coded according to the topic/subject of each of the questions. Lets say the first question was "How do you feel when you talk with strangers", the second question "How do you strangers react to you", and the third question "What surprises you when you communicate with strangers". So, each of the question has a different theme/subject/topic :-) and it was coded (or analysed) separately. Many thanks for your answers in advanced
It doesn't seem the correct word for the context. 'Theme' isn't a word that has any specific meaning in either data analysis or intelligence and seems inappropriate. The theme of something is often entirely arbitrary - for example, your English teacher may set a theme for a creative writing assignment but will grade your work in the same way as if any other theme had been chosen.
When it comes to surveys which will be subject to data analysis, the subject of questions is unlikely to be arbitrary. The topics of the questions are likely to be specific areas in which you hope to measure responses. You mentioned that the topics in your data are "distinct" but also "relevant", so I'm assuming that means relevant to some overarching common interest (which would be the 'theme', if anything).
This is more in the realm of jargon than plain English, but at data level, questions with measured answers (ie answers that can be scored, such as 1=bad, 5=excellent, and measures in between) are normally called 'metrics', 'key metrics', or 'key performance indicators'. These are then grouped into 'metric groups' or 'metric types'. So, let's say you were asking questions to see how students felt about their educational institution, and you asked separate sets of questions about the teaching staff, and then facilities. Those could be two sets of metrics.
If all of that is too much like jargon, perhaps instead of 'coded thematically', you could just say grouped by subject, which is plain English any audience can understand.