Définition Qualitative data

Qualitative data are attributes, the values of which (e.g. replies to a survey) can clearly be categorized. They cannot, however, be a mathematical value (=number). Typical examples of qualitative data are gender, religion or political affiliation. For these kinds of attributes, we can only reproduce percentage values as results of a survey (x in 100%).

Strictly speaking, ordinal data such as education level or personal satisfaction levels are qualitative data as well. We can establish a hierarchy of ordinal data; an exact numerical scaling is not possible though. One level of education is not "50% better" than another, it can only be specified as "superior to". Ordinal scales are not interval-scaled.

Nevertheless, ordinal features are described as 'seemingly quantitative', because approximately, they allow for mathematical operations. Thus, when comparing two groups, we can state that group A 'on average' has a higher level of education than group B. In order to achieve this, we would translate the ordinal levels of education into numerical values (1=lowest education level, 5=highest education level). From these numerical values, we can calculate a mean for each group and then compare both values. Technically speaking, this calculation is incorrect though, because the statement "group A has a higher education average, scoring 3.3 over group B's 3.0" actually implies that all educational levels have the same distances or intervals from each other (=are interval-scaled). 

Les définitions de notre encyclopédie sont des explications simplifiées de termes. Notre but est de rendre ces définitions compréhensibles pour un large public. Par conséquent, il est possible que certaines d’entre elles ne soient pas entièrement à la hauteur des standards scientifiques.