App B Measures of Variability Flashcards
What are measures of variability?
Statistics that show how different the numbers in a set of data are from one another.
What is the range in a data set?
The difference between the largest and the smallest values in a data set.
How do you calculate the range?
Subtract the smallest score from the largest score.
What is a shortcoming of the range as a measure of variability?
It is based only on two extreme scores and provides limited information about variability.
What are variance and standard deviation used for?
They are related measures of variability that address the shortcomings of the range.
How is a deviation score calculated?
By taking the difference between each score and the mean.
What problem arises when calculating the average of deviation scores?
The total of deviation scores is always 0, making the average useless for variability.
What is the variance?
The average of the squared deviation scores, indicating how different the numbers are from one another.
What is the formula for variance?
σ² = Σ(X - μ)² / N, where σ² is the variance, Σ is summation, and N is the number of observations.
Why is the standard deviation more useful than the variance?
The standard deviation is in the same metric as the original scores, while variance is not.
