Friday, January 11, 2008

Lecture 2 - Ch 3 - Shape of the Distribution

Although the skewness has a formal definition that we didn't discuss, we categorized the shape of a distribution as either symmetric, positive-skewed or negative-skewed.

Symmetric - mean = median
Positive-skewed - mean > median (think of this as having a longer tail on the right (positive) side of the distribution curve
Negative-skewed - mean < median (here there's a longer tail on the left (negative) side of the curve

A box-and-whiskers graph is a simple graphical summary of the skewness of the data.

Don't let this confuse you, but... Another measure of the shape of a distribution curve is the kurtosis. Sounds like a disease, doesn't it?

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