Descriptive Statistics and Distributions Flashcards

1
Q

biomedical data can be ___, ____, ____ or ____

A

biomedical data can be nominal, ordinal, interval or ratio

NOIR

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2
Q

if the measure is constrained to be positive and the mean is _____, the measure must be right skewed

A

if the measure is constrained to be positive and the mean is less than ~2x the standard deviation, the measure must be right skewed

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3
Q

describe application of the mean (average) and a con for using it

A
  • most common measure of central tendency
  • easy to model statistically; can be further averaged
  • only for interval and ratio measures
  • susceptible to extreme values
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4
Q

describe application of the median (central)

A
  • less affected by extreme values than the mean is
  • harder to model statistically: cannot be averaged
  • for ordinal, interval and ratio measures
  • commonly used for skewed measurements:
    • biomarker measurements
    • income
  • not susceptible to a few extreme values
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5
Q

describe application of the mode (most common)

A
  • not at all affected by extreme values
  • for all types of data: most often used for nominal data
  • can be misleading if there are many categories, or nonsensical for unrounded continuous variables
  • very difficult to model statistically
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6
Q

describe calculating the weighted mean

A
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7
Q

pooling is only for the ____

A

pooling is only​ for the mean

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8
Q

explain the different types of variability

A
  • range: “total variability”
    • indicates extreme values
  • interquartile range, IQR: “typical variability”
    • half of values fall within this range
    • not affected by a few extreme values
  • variance: “typical squared variability”
    • easy to work with statistically
    • more affected by extreme values than IQR is

standard deviation: square root of variance

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9
Q

describe the circumstances you would use the measures of variability

A
  • use the range for any ordinal data
  • use the interquartile range in the same settings you would use the median
  • use the variance and SD in the same settings you would use the mean
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10
Q

describe how to calculate range

A
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11
Q

describe how to calculate the interquartile range

A
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