statistics week1

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  1. parameter vs statistic
    • parameter: a numerical measurement describing some characteristic of a population
    • statistic: a numerical measurement describing some characteristic of a sample
  2. 2 types of quantitative data:
    • discrete: when the number of possible values is either a finite number or a "countable" number (0,1,2,3,...)
    • continous: infinitely many values that correspond to some continuous scale (2.243115 gallons of milk per day)
  3. 4 levels of measurement:
    • nominal: qualitative; data consists of names only and cannot be arranged in an ordering scheme (yes, no, undecided)
    • ordinal: qualitative; data that can be arranged in some order, but differences between values are meaningless (A, B, C, D, or F)
    • interval: quantitative; data can be arranged in order and difference between values has meaning. however, no natural zero starting point
    • ratio: quantitative; interval level except there is a natural zero starting point.
  4. observational studies vs experimental
    • observation: observing and measuring specific characteristics without attempting to modify the subject.
    • experimental: apply some treatment and then observe its effect on the subjects.
  5. types of sampling (5)
    • simple random sample: a sample of n subjects is selected so that every sample has the same chance of being chosen
    • systematic: select every kth element in the population
    • convenience: use results that are easy to get
    • stratified: subdivide the population into subgroups that share the same characteristics then draw a sample from each group. (male or female then 5% from each)
    • cluster: divide population area into sections then randomly select some of those clusters and all of their members
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statistics week1
statistics week1
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