Categorical vs Quantitative Data
In statistics, observations are recorded and analysed by means of variables. The variables are categorized into classes by the attributes they are used to measure. Categorical and quantitative are the two types of attributes measured by the statistical variables.
The data, or values of a qualitative variable are known as qualitative data, and the values of a qualitative variable are known as categorical or quantitative data.
Quantitative variable records the attributes that can be measured with a magnitude or size; i.e quantifiable. Variables measuring temperature, weight, mass or the height of a person, or the annual income of a household are quantitative variables. Not only all the values of these variables are numbers, but each number gives a sense of value too.
Qualitative variables measure attributes that can be given only as a property of the variables. The political affiliation of a person, nationality of a person, the favourite colour of a person, and the blood group of a patient can only be measured using qualitative attributes of each variable. Often these variables have limited number of possibilities and assume only one of the possible outcomes; i.e. the value is one of the given categories. Therefore these are commonly known as categorical variables too. These possible values can be numbers, letters, names, or any symbol.
The data in quantitative type belong to either one of the three following types; Ordinal, Interval, and Ratio. Categorical data always belong to nominal type. Above mentioned types are formally known as levels of measurement, and closely related to the way the measurements are made and the scale of each measurement.
Since the form of the data in the two categories is different, different techniques and methods are employed when gathering, analyzing, and describing.
Quantitative vs Categorical (qualitative) Data
• Quantitative data are information that has a sensible meaning when referring to its magnitude.
• Qualitative data are often information that takes values from a given set of categories, or groups.
• Quantitative data belong to ordinal, interval, or ratio classes of measurements while qualitative data belong to the nominal class of measurements.
• Methods used to analyse quantitative data are different from the methods used for categorical data, even if the principles are the same, at least the application have significant differences.
• Qualitative data are analysed using statistical methods in descriptive statistics, regression, time series, and many more. For categorical data, usually descriptive methods and graphical methods are employed. Some non-parametric tests are also used.