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Fall 2023. Recall that a measure of central tendency is a number which is “typical” of all the values of a variable in a data set. Another important measure is the amount of “spread” in the values of the variable. A measure of dispersion is a number which describes the spread of the data.
Lecture 4: Measure of Dispersion. Dispersion (a.k.a., variability, scatter, or spread)) characterizes how stretched or squeezed of the data. A measure of statistical dispersion is a nonnegative real number that is zero if all the data are the same and increases as the data become more diverse.
• Explain the purpose of measures of dispersion • Compute and interpret these measures – Range (R), interquartile range (Qor IQR) – Standard deviation (s), variance (s2) • Select an appropriate measure of dispersion and correctly calculate and interpret the statistic • Describe and explain the mathematical
The scatterness or variation of observations from their average are called the dispersion. There are different measures of dispersion like the range, the quartile deviation, the mean deviation and the standard deviation.
MEASURES OF DISPERSION 6.1. INTRODUCTION IN the previous chapter we considered the statistical parameters which could be used as a measure of the centre of a distribution, the most important being the mean. In this chapter are discussed some parameters which can be used as a measure of the spread of a distribu tion.
Depict minimum, first quartile, median, third quartile and maximum. The upper whisker (from the maximum to the third quartile) represents the upper 25% of the distribution. The interquartile range (IQR) represents the middle 50% of the data.
if many cases have observed values that are quite “far away” from many others (or from the average value), dispersion is high. A measure of dispersion provides a summary statistic that indicates the magnitude of such dispersion and, like a measure of central tendency, is a univariate statistic.
