statistics

• Statistics


  A branch of mathematics dealing with data collection, organization, analysis, interpretation and presentation
• Origin of the word "statistics"


  It comes from the word "state" because governments have been involved in statistical activities, especially the conduct of censuses either for military or taxation purposes
• Statistics enable us to

  • Characterize persons, objects, situations, and phenomena
  • Explain relationships among variables
  • Formulate objective assessments and comparisons
  • Make evidence-based decisions and predictions
• Preliminary in a Data Collection

  1. Confidentiality of Information

  2. Purpose
• Information collected in the data collection

  • CLASS STUDENT NUMBER
  • SEX
  • NUMBER OF SIBLINGS
  • WEIGHT (in kilograms)
  • HEIGHT (in centimeters)
  • AGE OF MOTHER (as of her last birthday in years)
  • USUAL DAILY ALLOWANCE IN SCHOOL (in pesos)
  • USUAL DAILY FOOD EXPENDITURE IN SCHOOL (in pesos)
  • USUAL NUMBER OF TEXT MESSAGES SENT IN A DAY
  • MOST PREFERRED COLOR
  • USUAL SLEEPING TIME
  • HAPPINESS INDEX FOR THE DAY
• Data


  A collection of facts from experiments, observations, sample surveys and censuses, and administrative reporting systems
• To contextualize data

  Identify its six W's: Who, What, When, Where, Why, How
• Population


  The totality of observations or elements from a set of data
• Sample


  One or more elements taken from the population for a specific purpose
• Parameter


  A numerical measure that describes the whole population
• Statistic


  A numerical description of the sample
• Variable


  A characteristic that is observable or measurable
• Qualitative Variable


  Variables that express a categorical attribute
• Quantitative Variable


  Numerical data - sizes are meaningful
• Discrete Data


  Data that can be counted
• Continuous Data


  Data that can be measured
• Nominal level


  Measurement arises when we have variables that are categorical and non numeric or where the numbers have no sense of ordering
• Ordinal level


  Deals with categorical variables like the nominal level, but in this level ordering is important
• Interval level


  One unit differs by a certain amount of degree from another unit
• Ratio level


  One unit has so many times as much of the property as does another unit
• Probability Sampling


  Each member of the population has a known probability of being selected in the sample (unbiased)
• Nonprobability Sampling


  There is bias in the selection and there is no recognized probability that one member will be included in the sample
• Probability Sampling Techniques

  1. Simple Random Sampling

  2. Systematic Random Sampling

  3. Stratified Sampling

  4. Cluster Sampling
• Nonprobability Sampling Techniques

  1. Convenience Sampling

  2. Purposive Sampling

  3. Snowball Sampling

  4. Quota Sampling
• Data Presentation Methods

  1. Textual or Narrative Presentation

  2. Tabular Presentation

  3. Graphical Presentation
• Common Parts of Statistical Table

  • Table Title
  • Column Header
  • Row Header
  • Body