Introduction to Biostatistics

• Statistics

  • field of study concerned with
  • (1) the collection, organization, and analysis of data
  • (2) the drawing of inferences about a body of data when only a part of the data is observed
• Biostatistics

  • tools of statistics when data analyzed are derived from the biological sciences and medicine
  • BIO means life; STATISTICS means data
  • science of summarizing data so that non-statistician can understand it
  • can be used as a tool in decision-making
• Data 

  • raw material of statistics
  • data as number:
  • from the taking of a measurement 
  • from the process of counting
• • Routinely kept records
  • records of day-to-day transactions of its activities
  • ex. hospital records & hospital accounting records
• • Surveys
  • ex. administrator of a clinic wishes to obtain information regarding the mode of transportation used by patients to visit the clinic
• • Experiments
  • ex. nurse may wish to know which of several strategies is best for maximizing patient compliance
• • External sources
  • data needed to answer a question may already exist in the form of published reports, commercially available data banks, or the research literature
• • Primary - first hand data gathered by the researcher
• • Secondary - data collected by someone else
• Variable

  • characteristic that takes on different values in different persons, places, or things
• • Qualitative variables - characteristics are not capable of being measured, convey information regarding attitude
• • Quantitative variables - convey information regarding amount 
• • Constant variable - value of a characteristic that remains the same from person to person, from time to time or from place to place
• • Random variable - characteristics takes on different values
• Discrete 

  • can assume a finite or countable number of values
  • characterized by gaps or interruptions in the values that it can assume
• Continuous 

  • can assume an infinite or other possible values
  • does not possess the gaps or interruptions
• Population

  • largest collection of entities for which we have an interest at a particular time
  • value is denoted by N
• Sample

  • part of a population
  • value is denoted by n
• Parameter

  • measure of a characteristic of a population
• I. Nominal

  • simply used as names or identifiers of a category
  • always qualitative
  • does not represent any amount or quantity
• II. Ordinal

  • represents an ordered series of relationships
  • may be qualitative or quantitative
• III. Interval

  • does not have a true-zero value or starting point
  • always qualitative
• IV. Ratio

  • modified interval level which includes zero as a starting point
  • always qualitative
• (1) Descriptive Statistics

  • methods of summarizing and presenting data
  • computation of measures of central tendency and variability
  • tabulation and graphical presentation
  • facilitate understanding, analysis, and interpretation of data
• (2) Inferential Statistics

  • methods of arriving at conclusions and generalizations about a target population based on information from a sample
  • estimation of parameters and hypotheses testing