BIOL 3P96 Lecture Notes - Lecture 16: Test Statistic, Multivariate Normal Distribution, Standard Error
26 Jul 2015
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Biol 3p96 lecture 16: correlation between numerical variables. Measures the strength and direction of the association between two numerical variables. Reflects the amount of scatter in a scatter plot of the two variables. Represented by (rho) in a population and r in a sample. Negative correlations indicate that as one variable increases, the other decreases. Positive correlations indicate that as one variable increases, the other also increases. Correlation coefficient ranges from -1 to +1, with a value of zero indicating no correlation. The closer the value is to -1 or +1, the less scatter there is in the points. All points lie along a straight line. Two variables may be strongly associated yet have no correlation (r = 0) if the relationship is nonlinear. Y i y 2 r= (x i x)(y i y ) Observations above the mean for both x and y will be in the upper right corner (two positive deviations = positive product)
