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Flashcards in Descriptive Statistics Deck (13)
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___________________ techniques include tables, frequency distributions, frequency polygons, measures of central tendency, and measures of variability.



When using a frequency polygon, scores are recorded on the _______________ axis (abscissa), while frequencies are coded on the _________________ axis (ordinate).

  • Horizontal
  • Vertical


_______________ refers to the relative peakedness of a distribution;

  • _______________: Distribution is MORE peaked than normal
  • _______________: Distribution is LESS peaked than normal
  • _______________: Distribution is normal

  • Kurtosis
  • Leptokurtic
  • Platykurtic
  • Mesokurtic


__________________ skewed distribution: Most of the scores are in the negative (low score) side of the distribution.



______________________ skewed distribution: Most of the scores are in the positive (high score) side of the distribution.


Note: "The tail that tells the tale."


Measures of Central Tendency:

  • ______________: The score or category that occurs most frequently; can have more than one; is susceptible to sampling fluctuations
  • ______________: Divides a distribution in half when the data have been ordered from low to high; is insensitive to outliers
  • ______________: (M or X-bar) the arithmetic average (M=ΣX/N); least susceptible to sampling fluctuations, but is affected by the magnitude of every score in the distribution

  • Mode
  • Median
  • Mean


The ________________ is the preferred measure of central tendency when the data is on an ordinal scale; the _________________ is preferred for interval and ratio scales.

  • Median
  • Mean


Measure of Central Tendency (from greatest to least) for skewed distributions:

  • ________________ skewed: Mean, Median, Mode
  • ________________ skewed: Mode, Median, Mean

  • Positively
  • Negatively


________________ is calculated by subtracting the lowest score in the distribution from the highest score.



Variance is calculated using the following formula:

S2 (Variance) =    SS    = Σ(X-M)2

                           N-1          N-1


  • SS = the _________________, which is calculated by subtracting the mean from each score to obtain deviation scores, squaring each deviation score, and then summing the squared deviation scores
  • N-1 = the _______________ minus 1 (when calculating sample variance; N when calculating population variance)

  • Sum of Squares
  • Number of observations


The ____________________ is more often used as a measure of variability, and is calculated by taking the square root of the variance, which converts it to the same unit of measurement as the original scores:

S = Square Root (SS/N-1)

Standard Deviation.


Identify the Areas Under the Normal Curve:

-1 to +1 SD: ___________%

-2 to +2 SD: __________%

-3 to +3 SD: __________%

  • 68.26%
  • 95.44%
  • 99.72%


When a constant is added/subtracted to every score in a distribution, the measures of __________________ change, but the measures of _______________ do not.  However, when each score is multiplied or divided by a constant, measures of both central tendency and variability are affected.

  • Central tendency
  • Variability