POLSCI 3N06 Lecture Notes - Interquartile Range, Normal Distribution, Standard Deviation
14 Feb 2014
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Political science 3n06 semester ii 2014 lecture 4a: probability and the normal curve. Description: measure of central tendency (what is typical?, measure of dispersion, need to be able to describe the shape of the distribution! Last week: measures of dispersion, interested in the variety. Is there a deal of spread: which measure of dispersion we can use. It"s based upon the level of measurement on the variable: it"s whether it"s at the nominal, ordinal or interval. Nominal level - variation ration (proportion of cases not in the mode) Ordinal level - range or the interquartile range. Interquartile or range - only uses two variables; we are still only building two scores within the variety. Different methods of calculating the variance: matters less and less the sample size, small sample sizes it makes a difference whether dividing by n n 1 o o s (standard deviation) s2( variance)
