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QMM240_W08_Data

QMM240_W08_Data - QMM240 Data and Data Collection Data and...

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QMM240 Data and Data Collection Statistical Methods for Business I - Lecture Notes Page: 1 Data and Data Collection Data: Plural of datum (Latin for "a given fact") Common use now is singular and plural The set of measurements obtained from a sample or census. The information used to make more informed decisions. Example: The taste preferences obtained in customer survey (sample) Salary for each employee in company (census) Reasons to Collect Data: Provide input to a study Measure performance Enhance decision making Population: The collection of things, individuals or subjects (People, Services) under study Members should have some common element Denote number of members as N Can have finite and infinite populations Examples: Students in QMM240, Customers of ABC Co. Bag of M&Ms Variable: Characteristic that describes a member in the population. Each population member has a measurable value for a variable Examples: Students in QMM240 : Birthplace, Age, Number of credits.
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QMM240 Data and Data Collection Statistical Methods for Business I - Lecture Notes Page: 2 Customers of Ikea : Income, Total purchases, Zip code. Bag of M&Ms : Color, weight, shell coverage ratio Attribute or Qualitative (Categorical) data Labels or names data Allows partitioning a population Non-numeric Example: Cars are blue, green and red Data Coding: May convert categorical data to numbers for analysis (Green = 1, Red = 2, Blue = 3) Binary coding : 0 or 1 Examples: 1 = employed, 0 = not employed 1 = married, 0 = not married 1 = male, 0 = female 1 = female, 0 = male Many mathematical operations such as averages may NOT make any sense for coded data. Coding does not make non-numeric data, numeric. Quantitative (Numerical) data Numerical description May allow uniquely identifying each member of population Two types of Numerical data: Continuous and discrete Example: The time to make the cappuccino was 47 seconds The customer purchased 2 items Sample: As a verb, "to sample" = Measuring a subset of the population As a noun, "sample" = subset of the population Used to project or estimate a characteristic of the population Denote sample size as n
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QMM240 Data and Data Collection Statistical Methods for Business I - Lecture Notes Page: 3 Measuring Variables: Collecting data May have error associated with measurements Each variable becomes column in the spreadsheet or database Observation: Each recorded value of a variable Case: All observations for a given member in the sample A row in the spreadsheet or database table Example : Special procedures in 2005 at Hope Hospital Population all special procedures HopeHospital.xls 1) How many variables?
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  • Winter '08
  • ISKEN

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