Descriptive Statistics (Measures of Central Tendency and Shapes of Distribution) Flashcards

1
Q

typical or most representative value of a group of scores; Mean, Median, Mode

A

Central Tendency

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2
Q

arithmetic average of a group of scores; sum of the scores divided by the number of scores; the balance point of a distribution

A

Mean (M)

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3
Q

μ

A

population mean

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4
Q

M

A

sample mean

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5
Q

an average in which each observation in the data set is assigned or multiplied by a weight before summing to a single average value

A

Weighted Mean

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6
Q

Characteristics of the Mean

A
  1. Changing a score in the distribution can affect the value of the mean
  2. Introducing a new score or removing a score can affect the value of the mean.
  3. Adding or subtracting a constant from each score will change the value of the mean.
  4. Multiplying or dividing each score by a constant will change the value of the mean
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7
Q

When to use the Mean?

A
  1. quantitative research, especially in psychological studies
  2. approximately normally distributed data
  3. with equal-interval variables: (Continuous Data/Variable &
    Interval/Ratio)
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8
Q

middle score when all the scores in a distribution are arranged from lowest to highest

A

Median (Mdn)

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9
Q

When to use the Median?

A
  1. with rank-ordered variables
  2. non-normal or skewed distributions
  3. when a distribution has one or more outliers
  4. rarely used in psychology research
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10
Q

score with an extreme (very high or very low) in relation to the other scores in the distribution.

A

outliers

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11
Q

value with the greatest frequency in the distribution

A

mode

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12
Q

When to use the Mode?

A
  1. with categorical variables (nominal)
  2. rarely used in psychology research
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13
Q

frequency distribution with one value clearly having a larger frequency than any other

A

Unimodal Distribution

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14
Q

frequency distribution with two approximately equal frequencies, each clearly larger than any the others

A

Bimodal Distribution

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15
Q

frequency distribution with two or more high frequencies separated by a lower frequency

A

Multimodal Distribution

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16
Q

frequency distribution in which all values have approximately the same frequency

A

Rectangular Distribution

17
Q

distribution in which the pattern of frequencies on the left and right side are mirror images of each other

A

Symmetrical Distribution

18
Q

distribution in which the scores pile up on one side of the middle and are spread out on the other side; distribution that is not symmetrical

A

Skewed Distribution

19
Q

the peak (highest frequency) in the distribution is on the left-hand side with tail tapering off the right

A

Positively Skewed Distribution

20
Q

a situation in which many scores pile up at the low end of a distribution (creating a skewness to the right) because it is not possible to have any lower score.

A

Floor Effect

21
Q

the peak (highest frequency) in the distribution is on the right-hand side with the tail tapering of the left

A

Negatively Skewed Distribution

22
Q

a situation in which many scores pile up at the high end of a distribution (creating a skewness to the left) because it is not possible to have a higher score.

A

Ceiling Effect

23
Q

specific, mathematically defined, bell-shaped frequency distribution that is symmetrical and unimodal; distributions observed in nature and in research commonly approximates it

A

Normal Curve

24
Q

extent to which a frequency distribution deviates from a normal curve in terms of whether its curve in the middle is more peaked or flat than the normal curve.

25
the scores are concentrated towards the mean
Leptokurtic
26
normal curve
Mesokurtic
27
the scores have an extremely large deviation from the mean
Platykurtic