Flashcards in Chapter 5 Deck (7)
a measure of the spread, or dispersion, of a set of data. Once the mean, median, and mode have been calculated, the central tendencies of the raw data are known.
a measure of variability used when data are ordinal, or when ratio or interval data are highly skewed; This range is the difference between the raw scores at the 75th (Q3) and the 25th (Q1) percentile points.
IQR = Q3−Q1
alternative measure of variability when using percentiles; which is half of the interquartile range. The formula is SIQR = (Q3−Q1)/2. This measure is used if a smaller indicator of the variability is desire
the average of the squared deviations from the mean. The symbol V is used for variance in this text; other texts may use the symbol S2; represented in algebraic terms
as follows: V =Σ(X−X)^2/N.
Sum of Squares
type of calculation where we add up squared values
the square root of the average of the squared deviations from the mean (i.e., it is the square root of the variance); applies to a population of scores