POLSCI 3N06 Lecture Notes - Lecture 2: Interquartile Range, Standard Deviation, Central Tendency
18 Apr 2016
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Political science 3n06 semester ii 2016 lecture 2 measures of dispersion. Measures of central tendency like the mean, median and mode only tell us part of the descriptive story. In fact, if we describe our variables using only the central tendency: our lone statistic may mislead rather than enlighten us. The central tendency tells us what is typical in the distribution. What is equally important to describing a distribution is what is different in the distribution. There are a number of different statistics that we can use to describe the variety, or variation, or spread, or dispersion in a distribution. The appropriate measure depends upon the level of measurement of the variable (amongst other considerations) The variation ratio can be used for nominal-level variables. Can be used for ordinal or interval-ratio level variables. Range = highest score lowest score. It gives a simple indication of the variety within a distribution. But it is also a limited indicator.
