Stats Test 1

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Stats Test 1
2012-02-22 00:22:47

Elementary Statistics ch 1, 2, 4
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  1. Statistics
    The collection, organization, and interpretation of data for the purposes of summarization (descriptive statistics) pool drawing conclusions about populations based on samples (inferential statistics)
  2. Population
    A collection of objects together with a certain characteristic; precisely defined collection of values
  3. Sample
    Part of a population
  4. Inference
    Decision making based on samples drawn from populations
  5. Random sample
    Each and every member of the population has an equal chance of being selected
  6. Internal validity
    The certainty that the observations in our sample group are accurate measurements (something that is not internally valid doesn't actually change the characteristic being observed)
  7. External validity
    The certainty that the methods and presence of the researcher is not affecting what is being studied
  8. Valid random sample
    A random sample that is both internally and externally valid
  9. The arithmetic mean or average value of a population
  10. Sample average is approximately equal to the population average
  11. Mean
    Sum of all values divided by the number of values
  12. Median
    The middle value when data is ordered from lowest to highest

    *if there are two middle values, we average the two
  13. Mode
    The most frequently occurring observation

    *There can be no mode or multiple modes
  14. Modal class
    The mode for grouped data
  15. Range
    The difference between the highest and lowest value in the data set
  16. Standard deviation
    A form of average distance from the mean

  17. Working backward
    If we know the percentage of data between 0 and z, we look up this area (in decimal form) in the table and determine the closest z value (choose higher value if midway)