COB 191 Chapter Notes - Chapter 3: Variance, Bias Of An Estimator, Central Tendency
Document Summary
Central tendency: single value used to describe center pt of data set. Mean: most common measure of central tendency; disadv: sensiive to outliers. Weighted mean: assign more weight to certain values and less to other. Median: middle value of data set; use when outliers are present because it"s not sensiive to outliers. Index pt: (i) used to determine the posiion of the median in the data set. Mode: value that appears most oten in data set; when describing central tendency for categorical data, mode is your only choice. = shows how much spread is present in data: Variance: measures the variability around data set"s mean. Standard deviaion: square root of variance; tells how far on average each data value is from the sample mean. Unbiased esimator: sample variance is an unbiased esimator of populaion variance b/c we"d expect the average of many sample variances taken from a populaion to equal true populaion variance.
