Lecture3 - CSC 5800: Intelligent Systems: Algorithms and...

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1 Lecture 3: Data CSC 5800: Intelligent Systems: Algorithms and Tools Acknowledgement: This lecture is partially based on the slides from Pang-Ning Tan, Michael Steinbach, and Vipin Kumar, “ Introduction to Data Mining”, Addison-Wesley (2005). Today’s Lecture…. . • Attributes and objects • Types of Data Sets • Data Quality issues
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2 What is Data? • Collection of data objects and their attributes • An attribute is a property or characteristic of an object – Examples: eye color of a person, temperature, etc. – Attribute is also known as variable, field, characteristic, or feature • A collection of attributes describe an object – Object is also known as record, point, case, sample, entity, or instance Tid Refund Marital Status Taxable Income Cheat 1 Yes Single 125K No 2 No Married 100K No 3 No Single 70K No 4 Yes Married 120K No 5 No Divorced 95K Yes 6 No Married 60K No 7 Yes Divorced 220K No 8 No Single 85K Yes 9 No Married 75K No 10 No Single 90K Yes Attributes Objects Attribute Values • Attribute values are numbers or symbols assigned to an attribute • Attribute is a characteristic/feature/property. • Distinction between attributes and attribute values – Same attribute can be mapped to different attribute values • Example: height can be measured in feet or meters – Different attributes can be mapped to the same set of values • Example: Attribute values for ID and age are integers • But properties of attribute values can be different – ID has no limit but age has a maximum and minimum value
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3 Types of Attributes – Nominal Examples: ID numbers, eye color, zip codes – Ordinal Examples: rankings (e.g., taste of potato chips on a scale from 1-10), grades, height in {tall, medium, short} – Interval Examples: calendar dates, temperatures in Celsius or Fahrenheit. – Ratio Examples: temperature in Kelvin, length, time, counts Properties of Attribute Values • The type of an attribute depends on which of the following properties it possesses: – Distinctness: = – Order: < > – Addition: + - – Multiplication: * / – Nominal attribute: distinctness – Ratio attribute: all 4 properties
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4 Attribute Type Description Examples Operations Nominal The values of a nominal attribute are just different names, i.e., nominal attributes provide only enough information to distinguish one object from another. (=, ) zip codes, employee ID numbers, eye color, sex: { male, female } mode, entropy, contingency correlation, χ 2 test Ordinal The values of an ordinal attribute provide enough information to order objects. (<, >) hardness of minerals, { good, better, best }, grades, street numbers
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This note was uploaded on 09/21/2010 for the course CS 5800 taught by Professor Reddy during the Fall '10 term at Wayne State University.

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Lecture3 - CSC 5800: Intelligent Systems: Algorithms and...

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