Stats - Unit 1

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Stats - Unit 1
2011-02-21 19:53:56

Statistics unit one definitions
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  1. Statistics (the study of)
    Science of collecting, organizing, summarizing, and analyzing data to draw conclusions and answer questions
  2. Population
    the entire group of people being studied
  3. Sample
    Subset of population that is being studied
  4. Individual
    A person or object that is a member of the poopulation being studied
  5. Statistic
    a numerical summary of a sample

  6. Parameter
    numerical summary of a population

  7. Descriptive Statistics
    Describe data through numerical summaries - tables and graphs
  8. Inferential Statistics
    Take a result form a sample - extend to the pop - measure reliability of result
  9. Variable
    • Characteristics of the individual within a population
    • EX weight, height, age
  10. Qualitative vs. Quantitative
    • Qualitative- classification based on a characteristic (gender, eye color)
    • Quantitative- numerical measurements of individuals (age, weight, shoe size)

    Difference is when added together, one means something, and the other does not or cannot be added together
  11. Discrete vs. Continuous
    • Discrete- an infinite # of values that are countable (# of facebook friends - cannot have half a fb friend)
    • Continuous- an infinite # of values that are not countable (weight, age - can weigh 110.5 lbs)
  12. What are the 5 types of sampling?
    • 1- simple random sampling
    • 2- systematic
    • 3- stratified
    • 4- cluster
    • 5- convenience
  13. Simple Random Sampling (SRS)
    equal chance for each person or group of people to be picked for the sample
  14. Systematic
    select every kth individual from the population

    EX randomly select a starting point and survey every 5th person
  15. Stratified
    divide population into non-overlapping homogenous groups - randomly select sample from every strata

    EX divide class into 2 strata (shoes & boots) then randomly select 10 students from each group = sample
  16. Cluster
    divide population into non-overlapping groups call clusters - randomly select clusters (not all are chosen) and sample every indivudual
  17. Convenience
    sampling whomever is convenient
  18. Histogram
    • Constructed by drawing rectangles for each class of data - height of rectangle is the frequency of the class.
    • Same width and always touching
  19. Lower vs. Upper limit
    • Lower- the smallest value within a class
    • Upper- the largest value within a class
  20. Class Width
    the difference between consecutive lower class limits

    class width = largest data value - smallest data value / number of classes
  21. Stem and Leaf Plot
    • -represent quantitative data graphically
    • -numbers on the left (stem) represent the first few digits
    • -number on the right (leaf) represent the last few digits
    • -leaves are stacked on the right side
  22. What are the measures of central tendency?
    • Mean
    • Median
    • Mode
  23. Population arithmetic mean
    • μ computed by using all of the individuals in a population
    • pop mean = paramater
  24. Sample arithmetic mean
    • x bar computed using sample data
    • samp mean = statistic