CRIM 320 Lecture Notes - Lecture 3: Null Hypothesis, Interval Ratio, Binomial Distribution
9 Mar 2016
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Document Summary
Measures of variability, distributions, and the normal curve. Range: the difference between the highest and lowest score, r= h-l, weakness, heavily influenced by outliers i. crude estimate of variability. Variance: represents the avg variability in a distribution. X x s 2= )2 / n s2= variance a: mean (x-_x)2 = sum of the squared deviations from the mean, n = sample size. Standard deviation: represents the avg variability in a distribution, addition 6th step: square root formula, sd= , no longer dealing with squared units, advantage: easier to interpret. Ve skewed: towards left: kurtosis: measure of height/ y axis i. leptokurtic: tallest peak, points on x axis are clustered in a single area resulting in a higher peak than the caricature found in a normal dis. 2. the distribution is more clustered around the mean ii. iii. normal platykurtic: lowest peak the pt in x ais are highly dispersed resulting in a lower peak.
