Types of Data Levels of Measurement Basic Vocabulary

Types of Data Levels of Measurement

Basic Vocabulary of Statistics VARIABLE A variable is a characteristic of an item or individual. DATA Data are the different values associated with a variable. OPERATIONAL DEFINITIONS Data values are meaningless unless their variables have operational definitions, universally accepted meanings that are clear to all associated with an analysis. Basic Business Statistics, 11 e © 2009 Prentice-Hall, Inc. . Chap 1 -2

Population vs. Sample Population Measures used to describe the population are called parameters Basic Business Statistics, 11 e © 2009 Prentice-Hall, Inc. . Sample Measures computed from sample data are called statistics Chap 1 -3

Types of Variables § Categorical (qualitative) variables have values that can only be placed into categories, such as “yes” and “no. ” They are not numbers. § Numerical (quantitative) variables have values that represent quantities. They are numbers. Basic Business Statistics, 11 e © 2009 Prentice-Hall, Inc. . Chap 1 -4

Types of Variables Categorical (qualitative) variables have values that can only be placed into categories. e. g. When do you buy a newspaper? M T W Th F Sa Su e. g. Do you have a driving licence? Yes No § Numerical (quantitative) variables are numbers. e. g. How many magazines do you buy a week? e. g. How long have you had a driving licence? e. g. How tall is the building? §

Types of Data Categorical Numerical Examples: n n n Discrete Marital Status Political Party Eye Colour (Defined categories) Examples: n n Basic Business Statistics, 11 e © 2009 Prentice-Hall, Inc. . Number of Children Defects per hour (Counted items) Continuous Examples: n n Weight Voltage (Measured characteristics) Chap 1 -6

More Types of Data n n Cross Sectional Data giving a situation at one moment in time n n Time Series Data Gives values of same variable (measured or counted) at different points in time

More Types of Data n n Cross Sectional Data giving a situation at one moment in time e. g. Destination of full-time first degree graduates n n Time Series Data Gives values of same variable (measured or counted) at different points in time e. g. Economic activity and inactivity of young people

Levels of Measurement. Numerical Data § A ratio scale is an ordered scale in which the difference between the measurements is a meaningful quantity and the measurements have a true zero point. § An interval scale is an ordered scale in which the difference between measurements is a meaningful quantity but the measurements do not have a true zero point. Basic Business Statistics, 11 e © 2009 Prentice-Hall, Inc. . Chap 1 -9

Interval and Ratio Scales Basic Business Statistics, 11 e © 2009 Prentice-Hall, Inc. .

Levels of Measurement. Categorical Data § A nominal scale classifies data into distinct categories in which no ranking is implied. Categorical Variables Categories Personal Computer Ownership Yes / No Type of Stocks Owned Growth Value Other Internet Provider Microsoft Network / AOL/ Other Basic Business Statistics, 11 e © 2009 Prentice-Hall, Inc. . Chap 1 -11

Levels of Measurement. Categorical Data § An ordinal scale classifies data into distinct categories in which ranking is implied Categorical Variable Ordered Categories Service Excellent, Good, Fair, Poor Product satisfaction Satisfied, Neutral, Dissatisfied Size Extra large, Large, Medium, Small Standard & Poor’s bond ratings AAA, A, BBB, B, CCC, C, DDD, D Student Grades A, B, C, D, F Basic Business Statistics, 11 e © 2009 Prentice-Hall, Inc. . Chap 1 -12