MGCR 271 Lecture Notes - Lecture 1: Sampling Distribution, Interquartile Range, Standard Deviation
Document Summary
Measures of position - mean, median (always order data), mode, percentile (the value below which p% of observations lie) q1: 25th p median of data below q2. Q3: 75th p median of data above q2. Variances can only be variance) s2 = (cid:4666)(cid:2206) (cid:2206) (cid:4667)(cid:2779) (cid:2196) (cid:2778) compared if they have the same unit of measurement and their means are equal. (cid:2159)=(cid:2778)(cid:2777)(cid:2777) (cid:4672)(cid:2201)(cid:2206) (cid:4673: interquartile range: the range of the middle 50% of observations. Graphical analysis - box plot (find median, then q1, q3), histograms. 1. mean = median = mode symmetrical distribution (5 number summary: mean > median positively skewed (skewed to the right, mean < median negatively skewed (skewed to the left) The normal distribution - symmetric curves with an area of 1. Mean: determines where the curve is centered, it shifts the distribution. Standard deviation: determines how spread the curve is (large=wide, small=tall) X-axis: values of each characteristic, y-axis: relative likelihood of occurrence.
