STATS AND PROB

• Universe


  The collection or set of units or entities from whom data is obtained
• Variables

  • age
  • number of siblings
  • Weight
  • Height
  • age of mother
  • usual daily allowance in school
  • usual daily food expenditure in school
  • usual number of text messages sent in a day
  • most preferred color
  • usual sleeping time
  • happiness index for the day
• Sample

  A subgroup or subset of a universe or population
• Quantitative Variables


  Numerical data with meaningful sizes, answer questions like "how much" or "how many", have actual units of measure
• Data


  Facts and figures that are presented, collected, and analyzed; can be numeric or non-numeric and must be contextualized
• Discrete Data


  Data that can be counted, assume only a countable number of values
• Contextualization of Data

  The process of putting meaning on data by identifying the six W’s: Who, What, When, Where, Why, How
• Variable


  A characteristic that is observable or measurable in every unit of the universe
• Population


  The set of all possible values of a variable
• Quantitative Variables

  • Height
  • Weight
  • number of registered cars
  • household size
  • total household expenditures/income of survey respondents
• Qualitative Variables


  Express categorical attributes, do not strictly take on numeric values, sometimes have a sense of ordering
• Quantitative variables

  • total household expenditures/income of survey respondents
• Discrete Data


  Data that can be counted and assume only a finite or infinitely countable number of values
• Nominal level of measurement arises when variables are categorical and non-numeric or where the numbers have no sense of ordering
• Continuous Data


  Data that can be measured and have uncountably infinite possible values
• Interval level of measurement tells us that one unit differs by a certain amount of degree from another unit and possesses properties of the ordinal level with an additional property of knowing the difference between units
• Ratio level of measurement tells us that one unit has so many times as much of the property as another unit, possesses a meaningful absolute zero point, and allows all arithmetic operations
• Interval level does not possess an absolute zero, where zero is arbitrary and does not mean the value does not exist
• Ordinal level of measurement deals with categorical variables where ordering is important and values could be ranked
• Continuous Data


  • the exact height of a survey respondent
  • the exact volume of some liquid substance
• Quantitative data

  • Can be further classified into Discrete Data and Continuous Data
• Discrete Data


  • the number of days for cellphones to fail
  • the ages of survey respondents measured to the nearest year
  • the number of patients in a hospital
• Examples of Levels of Measurement

  • highest educational attainment (ordinal)
  • predominant hair color (nominal)
  • body temperature (interval)
  • civil status (nominal)
  • brand of laundry soap being used (nominal)
  • total household expenditures last month in pesos (ratio)
  • number of children in a household (ratio)
  • number of hours standing in queue while waiting to be served by a bank teller (ratio)
  • amount spent on rice last week by a household (ratio)
  • distance travelled by the teacher in going to school (ratio)
  • time consumed on Facebook on a particular day (ratio)