Page 16 - Demo

%u062c%u0645%u064a%u0639 %u0627%u0644%u062d%u0642%u0648%u0642 %u0645%u062d%u0641%u0648%u0638%u0629 %u0640 %u0627%u0625%u0644%u0639%u062a%u062f%u0627%u0621 %u0639%u0649%u0644 %u062d%u0642 %u0627%u0645%u0644%u0624%u0644%u0641 %u0628%u0627%u0644%u0646%u0633%u062e %u0623%u0648 %u0627%u0644%u0637%u0628%u0627%u0639%u0629 %u064a%u0639%u0631%u0636 %u0641%u0627%u0639%u0644%u0647 %u0644%u0644%u0645%u0633%u0627%u0626%u0644%u0629 %u0627%u0644%u0642%u0627%u0646%u0648%u0646%u064a%u062916Chapter TwoExploring the DataData sets are made up of data objects. A data object represents an Entity (Entity refers to any object or a thing that can be uniquely identified in the real world. It Can be anything (including an abstract thing!). An entity must be distinguished from other entities to show it's unique existence) foe example: an entity in a sales database, the objects may be customers, store items, and sales; in a medical database, the objects may be patients; in a university database, the objects may be students, professors and courses. Data objects are typically described by attributes. An attribute is a data field, representing a characteristic or feature of a data object, for example: attributes describing a customer object can include customer ID, name, and address. The distribution of data involving one attribute is called univariate. A bivariate distribution involves two attributes. I. Types of attributes 1- Nominal Attributes: Nominal means %u201crelating to names.%u201d The values of a nominal attribute are symbols or names of things. Each value represents category, code, or state. Nominal attributes are also referred to as categorical. For example: - the attribute marital status can take on the values single, married, divorced, and widowed. 2 - Binary Attributes: A binary attribute is a nominal attribute with only two categories or states: 0 or 1, where 0 typically means that the attribute is absent, and 1 means that it is present. Binary attributes are referred to as Boolean if the two states correspond to true and false. For example: - given the attribute smoker describing a patient object, 1 indicates that the patient smokes, while 0 indicates that the patient does not. 3- Ordinal Attributes: An ordinal attribute is an attribute with possible values that have a meaningful order or ranking among them. For example: - drink size has three possible values: small, medium, and large; grade (e.g., A+, A, A%u2212, B+, and so on)