Qualitative means describing qualities — interviews and observations, not numbers. Qualitative research, qualitative data, a qualitative difference.
It answers why and how where quantitative work answers how many, and the two are complements rather than rivals. A qualitative difference is one of kind rather than degree, which is a useful distinction well outside research.
1adjectivequalitativeDescribing qualities rather than numbers.
“The researchers did qualitative interviews to learn how patients felt about their treatment.”
qualitative is a quality of method.
Medieval Latin qualitativus comes from qualitas, quality, from qualis, of what kind.
Proto-Indo-European
*kʷ-
Proto-Indo-European
*kʷo- — who, how
Latin
quālitās
Old French
qualité
Middle English
qualite
English
quality
English, today
qualitative
Built from
From Latin - (or Medieval Latin -) quālitātīvus. Equivalent to quality + -ative. quality comes from Middle English qualite, from Old French qualité, from Latin quālitās, from quālis (“of what kind”), from Proto-Indo-European kʷo- (“who, how”). Cicero coined qualitas as a calque to translate the Ancient Greek - word ποιότης (“quality”), coined by Plato from ποῖος (“of what nature, of what kind”).
Etymology from Wiktionary, CC BY-SA