1. Data
    collections of observations ( such as measurements, genders, survey responses)
  2. Statiscs
    the science of planning studies and experiments, obtaining data, and then organizing, summaraizing presenting, analyzing, interpreting, and drawing conclusions based on the data
  3. population
    the complete collection of all individuals (scores, people, measurements, and so on) to be studied; the collection is complete in the sense that it includes all of the individuals to be studied
  4. census
    collection of data from every member of a population
  5. Sample
    subcollection of members selected from a population
  6. Parameter
    a numerical measurement describing some characteristics of a pupulation
  7. statistic
    a numerical measurement describing some characteristic of a sample
  8. quantitative data
    consists of numbers representing counts or measurements
  9. qualitative data
    consists of names or labels; categorical
  10. Quantitative data can either be
    discrete or continueous
  11. Discrete data
    • result when the number of possible values is either a finite number or a countable number
    • (i.e. the number of possible values is 0,1,2,3,...)

    Example: The number of eggs that a hen lays
  12. Continuous (numerical) data
    result from infinitely many possible values that correspond to some continuous scale that covers a range of values without gaps, interruptions, or jumps
  13. Nominal level
    characterized by data that consist of names, labels, or categories only, and the data cannot be arranged in an ordering scheme ( such as low to high)

    Example: Survey responses yes, no, undecided
  14. Ordinal level of measurement
    involves data that can be arranged in some order, but differences between data values either cannot be determined or are meaningless

    Example: Course grades A, B, C, D, or F
  15. Interval level of measurement
    like the ordinal level, with the additional property that the difference between any two data values is meaningful, however, there is no natural zero starting point ( where none of the quantity is present)

    Example: Years 1000, 200, 1776
  16. Ratio level of measurement
    The interval level with the additional property that there is also a natural zero starting point ( where zero indicates that none of the quantity is present); for values at this level, differences and ratios are meaningful

    Example: Prices of college textbooks (0$ represents no cost, a $100 book costs twice as much as a $50 book)
  17. Nominal
    • Nominal- categories only
    • Ordinal- categories with some order
    • Interval- differences but no natural starting point
    • Ratio- differences and a natural starting point
  18. Observational study
    observing and measuring specific characteristics without attempting to modify the subjects being studied
  19. Experiment
    apply some treatment and then observe its effects on the subjects; (subjects in experiments are called experimental units)
  20. Simple random sample
    of n subjects selected in such a way that every possible sample of the same size n has the same chance of being chosen
  21. Systematic sampling
    select some starting point and then select every kth element in the population
  22. Convinence sampling
    use results that are easy to get
  23. Stratified sampling
    subdivide the pupulation in to atleast two different subgroups that share the same characteristics, then draw a sample from each subgroup
  24. Cluster sampling
    divide the pupulation area into sections (clusters); randomly select some of those clusters choose all members from selected clusters
  25. Multistage sampling
    collect data by using some comination of basic sampling methods

    In multistage sample design, pollsters select a sample in different stages, and each stage might use different methods of sampling
  26. Cross sectional study
    data are obseved, measured, and collected at one point in time
  27. Retrospective ( or case control) study
    data are collected from the past by going back in time ( examine records, interviews,...)
  28. Prospective ( or longitudinal or cohort) study
    data are collected in the future from groups of sharing common factors ( called cohorts)
  29. Randomization
    is used when subjects are assigned to different gropus through a process of random selection. THe logic is to use chance as a way to create two gropus that are similar
  30. Replication
    the repetition of an experiment on more than one subject
  31. Blinding
    technique in which the subject doesn't know whether he or she is recieving a treatment or a placebo
  32. Double blind
    blinding occurs at two levels:

    • 1) the subject doesn't know whether he or she is receiving the treatment or a placebo
    • 2) the experimenter does not know whether he or she is administering the treatment or the placebo
  33. Confouding
    occurs in an experiment when the experimienter is not able to distinguish between the effects or different factors
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