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Variability - Coggle Diagram
Variability
Standard Deviation
- Find the distance from the mean is to determine deviation for each individual score
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- or + = direction from mean
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- Average of deviation scores doesn't work as a measure because it is always zero
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Using squared values, compute mean squared deviation = Variance
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- Find the square root of the variance to obtain standard deviation
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Measurements
Populations
Sum of Squared Deviation (SS): variance = mean squared deviation = sum of squared deviations divided by the number scores
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Population Variance: represented by the Greek O symbol which is squared and equals the mean squared distance from the mean
Population Standard Deviation: represented by the Greek O symbol and equals the square root of the population variance
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Samples
Sample variance: represented by the symbol s squared and equals the mean squared distance from the mean
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Sample Standard Deviation: represented by the symbol s and equal the square root of the sample variance
Degrees of Freedom: determines the number of scores in the sample that are independent and free to vary df=n-1
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Variability: provides quantitative measure of the differences between scores in a distribution & describes the degree to which the scores are spread out or clustered together
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- measures how well an individual score represents the entire distribution
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