To data professionals, "data" implies some sort of structure with defined records and variables. In this context, quantitative variables are numbers (such as price, income, age) and qualitative variables are non-numbers (color, country, gender, payment method). Depending on the lingo in your particular world, qualitative data could also be called nominal data or categorical data but it's still structured data.
However, some fields use the term "qualitative data" differently. Their text or observations aren't easily codified into records and variables but they still examine large segments of data to discern patterns and themes. Philosophers might read Plato, Hobbes, Smith, and Marx to generate theories and find text passages to support, or refute, those theories.
Modern technology can be used to bridge these approaches (i.e. the digital humanities). There are tools available to process online comments or customer reviews and determine how many are "positive" but some questions and some data simply don't lend themselves to any sort of structured data methods.
Let's use the Bible as an example. One could ask "How many times is the word money in the Bible?" Since the Bible wasn't written in English, we'd first have to agree on which translation we're going to use. Then it wouldn't be difficult to process every single word and count the number of times "money" occurs. It's no surprise that this has already been done. I suppose it's interesting that the King James version uses "money" 140 times, but I'm not sure that this mini-fact is particularly useful.
There are other words for "money". The Bible might mention payment, wages, debt, inheritance, silver, gold, ... This source tells us that there are over 2300 verses in Bible that mention "money, wealth, or possessions".
But are "possessions" and "money" really the same thing? This analysis requires another step. As before, we'd have to agree on which translation to use but we'd also have to agree on a list of synonyms for "money". We might even come up with an ordinal scale for whether a word is a true equivalent or simply related. Then, as with the previous question, a program could process every word in the text and count how many times "money" and each synonym occurred.
In both of these examples, it's possible to process the Biblical text as more or less traditional data but the results aren't all that useful.
A much more interesting question is "What does the Bible teach about money?" Many have attempted to answer that question, but none of them were able to do so with traditional statistical or data analysis tools.
Data professionals often aren't comfortable with this type of qualitative analysis. It's too fuzzy or too touchy-feely. However, it's likely that the people data professionals report to are using all kinds of "fuzzy" analysis so it might be wise to study some fields where qualitative analysis is commonly used.
In Part 2, I'll tell a story of qualitative analysis and decision making. In Part 3, I'll do my own qualitative analysis.