Qualitative
Encyclopedia
The term qualitative is used to describe certain types of information
. The term is distinguished from the term quantitative data
, in which items are described in terms of quantity
and in which a range numerical values are used without implying that a particular numerical value refers to a particular distinct category. However, data originally obtained as qualitative information about individual items may give rise to quantitative data if they are summarised by means of counts; and conversely, data that are originally quantitative are sometimes grouped into categories to become qualitative data (for example, income below $20,000, income between $20,000 and $80,000, and income above $80,000).
Qualitative data describe items in terms of some quality or categorization that in some cases may be 'informal' or may use relatively ill-defined characteristics such as warmth and flavor; such subjective
data are sometimes of less value to scientific research
than quantitative data. However, qualitative data can include well-defined concepts such as gender, nationality or commodity type. Qualitative data can be binary (pass-fail, yes-no, etc.) or categorical data
.
In regression analysis
, dummy variables are a type of qualitative data. For example, if various features are observed about each of various human subjects, one such feature might be gender, in which case a dummy variable can be constructed that equals 0 if the subject is male and equals 1 if the subject is female. Then this dummy variable can be used as an independent variable
(explanatory variable) in an ordinary least squares
regression. Dummy variables can also be used as dependent variables, in which case the probit or logistic
regression technique would typically be used.
Information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...
. The term is distinguished from the term quantitative data
Numerical data
Numerical data is data measured or identified on a numerical scale. Numerical data can be analyzed using statistical methods, and results can be displayed using tables, charts, histograms and graphs. For example, a researcher will ask a questions to a participant that include words how often, how...
, in which items are described in terms of quantity
Quantity
Quantity is a property that can exist as a magnitude or multitude. Quantities can be compared in terms of "more" or "less" or "equal", or by assigning a numerical value in terms of a unit of measurement. Quantity is among the basic classes of things along with quality, substance, change, and relation...
and in which a range numerical values are used without implying that a particular numerical value refers to a particular distinct category. However, data originally obtained as qualitative information about individual items may give rise to quantitative data if they are summarised by means of counts; and conversely, data that are originally quantitative are sometimes grouped into categories to become qualitative data (for example, income below $20,000, income between $20,000 and $80,000, and income above $80,000).
Qualitative data describe items in terms of some quality or categorization that in some cases may be 'informal' or may use relatively ill-defined characteristics such as warmth and flavor; such subjective
Subject (philosophy)
In philosophy, a subject is a being that has subjective experiences, subjective consciousness or a relationship with another entity . A subject is an observer and an object is a thing observed...
data are sometimes of less value to scientific research
Science
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...
than quantitative data. However, qualitative data can include well-defined concepts such as gender, nationality or commodity type. Qualitative data can be binary (pass-fail, yes-no, etc.) or categorical data
Categorical data
In statistics, categorical data is that part of an observed dataset that consists of categorical variables, or for data that has been converted into that form, for example as grouped data...
.
In regression analysis
Regression analysis
In statistics, regression analysis includes many techniques for modeling and analyzing several variables, when the focus is on the relationship between a dependent variable and one or more independent variables...
, dummy variables are a type of qualitative data. For example, if various features are observed about each of various human subjects, one such feature might be gender, in which case a dummy variable can be constructed that equals 0 if the subject is male and equals 1 if the subject is female. Then this dummy variable can be used as an independent variable
Independent variable
The terms "dependent variable" and "independent variable" are used in similar but subtly different ways in mathematics and statistics as part of the standard terminology in those subjects...
(explanatory variable) in an ordinary least squares
Ordinary least squares
In statistics, ordinary least squares or linear least squares is a method for estimating the unknown parameters in a linear regression model. This method minimizes the sum of squared vertical distances between the observed responses in the dataset and the responses predicted by the linear...
regression. Dummy variables can also be used as dependent variables, in which case the probit or logistic
Logistic regression
In statistics, logistic regression is used for prediction of the probability of occurrence of an event by fitting data to a logit function logistic curve. It is a generalized linear model used for binomial regression...
regression technique would typically be used.