Statistics Exam 1

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Anonymous
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72615
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Statistics Exam 1
Updated:
2011-03-13 16:49:50
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Statistics
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  1. z-score:

    represents number of standard deviations a data value falls above or below the mean.

    • z= (X-μ)/σ
    • X= score
    • μ= mean
    • σ= standard deviation
  2. Percentile:
    divides a distribution into 100 equal parts.

    Percentile= [((# of values less than X) + .5)/total # of values] * 100%
  3. Outlier:
    extremely high or low value in a set of data
  4. Normal graph:
    Bell-shaped
  5. Normal Rule:
    given to a normal (bell-shaped) distribution

    • | | | | I | | | |
    • [ 68%]
    • [ 95% ]
    • [ 99.7% ]
  6. Stem and leaf plot:
    • First digit on one side, second digit(s) on the other side.
    • ex.: 18 24 25 28 39 45 46 46 49

    • 1 | 8
    • 2 | 4 5 8
    • 3 | 9
    • 4 | 5 6 6 9
  7. Nominal
    • No order
    • ex: religion, race, hair color, gender
  8. Ordinal:
    • low detail order
    • ex: sequels, seasons, grades, months, alphabet
  9. Intervals:
    • High detail oorder, 0≠ nothing
    • ex: temperature, clock time, years, IQ
  10. Ratio:
    • high detail order, 0= nothing
    • ex: height, speed, salary, age
  11. Categorical:
    • -class
    • -frequency
    • -percent
  12. Ungrouped:
    • -class
    • -class boundaries (the x.5 numbers above and below each class)
    • -frequency
    • -cumulative frequency (total up to a certain point; add number from the class before)

    *list classes not listed or classes in between
  13. Grouped:
    • -class
    • -class boundaries (x.5 above and below number)
    • -frequency
    • -cumulative frequency (add frequency from class before)
    • -relative frequency (frequency÷total from cumulative frequency)
    • -cumulative relative frequency
  14. Histogram:
    bar graph
  15. Frequency polygon:
    line graph that originates from 0 before first value and ends at 0 after last value.
  16. cumulative frequency graph:
    line graph that originates from 0 before first value and ends with a horizontal line after last value.
  17. Nominal:
    ordinal:
    interval:
    ratio:
    • mode
    • median
    • (symmetrical) mean; (skewed) median
    • (symmetrical) mean; (skewed) median
  18. Pareto chart:
    bar graph used to show frequencies for nominal or qualitative variables.
  19. Time series graph:
    line graph used to show a pattern or trend that occurs over a period of time. Doesn't originate from 0 and ends at last value.
  20. Pie graph:
    used to show the relationship between the parts and the whole.
  21. Mean (μ) rounding rule:
    round to one more decimal place than occurs in the raw data.
  22. Midrange:
    average of highest and lowest value.
  23. Weighted Mean:
    sum of (weights*values)÷sum of weights
  24. Variance:
    the average of the squares of each value's distance from the mean. σ^2

    • ex: (0+2+0+0+1+1+0)^2 ÷ 7
    • σ^2= 6/7
  25. Standard deviation:
    the square root of the variance. σ
  26. rounding rule for variance and standard deviation:
    round to one more decimal place than occurs in raw data
  27. If the word "sample" is used in description:
    while doing the mean, subtract 1 from the bottom number in the division.

    • ex: 0+4+0+0+1+1+0 ÷ 7-1
    • variance: s^2= 6/6= 1
    • std. deviation: s= 1
  28. the coefficient of variation:
    • CVar= (σ ÷ μ) * 100%
    • μ: mean
    • σ: std. deviation

    When comparing two variations, the higher number is more variable.

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