STATS 10 Chapter Notes - Chapter 3: Quartile, Standard Deviation, Interquartile Range
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Chapter 3 numerical summaries of center and variation. A number that measures how far away the typical observation is from the mean. A measurement converted to standard units is called z-score z-scores. Sd measures how spread out observations are w/ respect to the mean so useless if (cid:449)e do(cid:374)(cid:859)t use the (cid:373)ea(cid:374) Use interquartile range (iqr) for skewed distributions that we use the median to measure the center in. Iqr tells us how much space the middle 50% of the data occupy to find iqr: cut distribution into 4 equal parts (4 25%s) Iqr = the middle 2 parts = q3 q1. To find the quartiles: find the median (aka q2, which cuts the data into 2, cut first half up to the median. The cut is q1: which is also the median of the lower half of the data, cut second half = q3. The distance spanned by the entire data set.
