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# Observation

An observation or a data point is a set of one or more measurements on a single member of a population. Each measurement of an observation represents the value of a variable. This is usually called a data value. For example, the following data set represents the salary and the bank account balance at the end of each month of some individual.
Salary Bank Account Balance
April
May
June
July
A list of observations of a data set can be represented in a table. In the example, an observation corresponds to a particular month. Therefore, there are exactly observations. Each observation contains variables, salary and bank account balance.
Observations are usually collected by conducting a survey, an observational study, or an experiment.