M2L6: Measures of Variability Flashcards
show us how the scores in a set are scattered or distributed around the mean
Measures of variability or dispersion
Usually, this is defined in terms of distance. It tells how much distance to expect between one score and another.
Variability
It provides a quantitative measure of the differences between scores in a distribution and describes the degree to which the scores are spread out or clustered together.
Measures of variability or dispersion
Measures of variability tells whether the scores are clustered close together or are spread out over a large distance.
True
measures how well an individual score represents the entire distribution
Variability
This aspect of variability is very important for inferential statistics in which relatively small samples are used to answer questions about populations.
True
3 Measures of variability
1) range
2) standard deviation
3) variance
refers to the highest score minus the lowest score
Range
the difference between the largest score (Xmax) and the smallest score (Xmin)
Range
is the distance between the lower quartile and the upper quartile
Interquartile range or IQR
It is the spread in the middle half of a data set.
Interquartile range or IQR
It is a measure of variability, based on dividing a data set into quartiles.
Interquartile range or IQR
divide a rank-ordered data set into four equal parts
Quartile
is the “middle” value in the first half of the rank-ordered data set
Q1
is the median value in the set.
Q2
is the “middle” value in the second half of the rank-ordered data set.
Q3
The interquartile range is equal to
Q3 - Q1
equals the mean of the squared deviations
Variance
Variance is the average squared distance from the mean
True
is a measure of variability that tells us how the scores cluster around the mean
Standard deviation
The standard deviation is the most commonly used and the most important measure of variability.
True
Standard deviation uses the ____ of the distribution as a reference point and measures variability by considering the ________ between each score and the mean
mean, distance
In simple terms, the standard deviation provides a measure of the standard or average, distance from the mean, and describes whether the scores are clustered closely around the mean or are widely scattered.
True
Remember that the purpose of standard deviation is to measure the standard distance from the ____.
mean
It is important to consider other
characteristics of the distribution of scores
beside the mean.
True
The difference between the three sets lies in ___________.
variability
