Dummy Definitions

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Dummy Definitions
2013-08-18 14:45:35

Dummy definitions
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  1. Response Rate
    The number of respondents  divided by the number of surveys sent out.
  2. Scientific Method
    Asking questions, doing studies, collecting evidence, analyzing the evidence, and making conclusions
  3. Population
    The group of individuals that you wish to study in order to answer your research question
  4. Sample
    Select a small number of individuals from the population, study those individuals, and use that information to draw conclusions about the whole population.
  5. Random Sample
    Gives every member of the population an equal chance of being selected, and it uses some mechanism of chance to choose them.
  6. Bias
    A systematic favoritism that is present in the data collection process, resulting in lopsided misleading results

    • - In the way the sample is selected
    • - in the way the data are collected
  7. Data
    The actual measurements that you get through your study {Singular is datum}

    • - Numerical Data
    • - Categorical Data {Qualitative Data}
  8. Statistic
    A number that summarizes the datta collected from a sample
  9. Census
    Collect data from the entire population
  10. Parameter
    The number from the summary of all the census information
  11. Mean
    The sum of all numbers divided by te total number of numbers

  12. Median
    The center of a numerical data set. The point at which there are equal number of data points whose values lie above and blow the median value
  13. Standard Deviation
    A measurement of the variability {or spread} among the numbers in a data set.

    A standard {typical} amount of deviation {distance} from the average {or mean}.

    The average distance from the mean

    • n = number of values in dataset
    •  = the average of all the values
    • x = each value in the data set
  14. Empirical Rule
    95% of the data will fall within 2 standard deviations of the mean
  15. Percentile
    The percentage of values in the data set that fall below that certain score.

    90th percentile means 90% of the people scored lower than you did
  16. Ratio
    A fraction that divides two quantities

    300 girls and 200 boys is a ratio of 3:2
  17. Rate
    A ratio that reflects some quantity per a certain unit

    • a car goes 60 miles per hour
    • burglary rate is 3 per 1,000 homes
  18. Percentatge
    A number between 0 and 100 that reflects a portion of the whole
  19. Percent increase
    increase from 50 to 60

    • (60 - 50)÷50 
    • 10÷50 = 0.20 or 20%
  20. Percent of whole
    • The #1 comes up 468 times out of 4,839
    • The #2 comes up 513 times out of 4,839

    The difference in the number of times each number is drawn:

    • 513-468= 45
    • 45÷4,839= 0.009 { of 1%}
  21. Relative  Standing
    How an individual data value compares to the rest of the group. 

    Determined by percentiles
  22. Standard Score
    The number of standard deviations above or below the mean {without caring what the standard deviation or mean actually are}

    The answer is expressed as "score is 1 standard deviation below the mean" "Score is 2 standard deviations above the mean"

    Standard Score =

    •  = mean
    •  = Standard deviation
  23. Probablility of an Outcome
    The percentage of times tat the outcome is expected to happen.

    The number of ways that the outcome can happen ÷  the total number of possible outcomes.

    Rolling a 1 on a dice = 1 out of 6 or 16.7%
  24. Central Limit Theorem
    The distribution of all sample means (or proportions) is normal as long as the sample sizes are large enough
  25. Sample Error
    Measures the variability of a sample means

    Sample error = Standard Deviation
  26. Sampling Distribution
    A listing of all the values that a sample mean can take on and how often those values can occur
  27. Margin of Error
    • The number of standard errors added or subtracted