BA2300 Ch.3 P1

mean

average of all the data values

sample mean

the arithmetic average value of the responses on a variable

population mean

the sum of the values in the population divided by the population size

median

value that is in the middle when the data is arranged in ascending order

when is a median used

whenever a data set has extreme values

what is the median used for most often

annual income and property value data

trimmed mean

obtained by deleting a percentage of the smallest and largest values from a data set and then computing the mean of the remaining values

mode

The value that occurs most frequently in a given data set.

bimodal

distributions with two modes

multimodal

distributions with more than two modes

weighted mean

the mean obtained by assigning each observation a weight that reflects its importance

percentiles

provides information about how the data are spread over the interval from the smallest value to the largest value

quartiles

specific percentiles

first quartile = 25th percentile
second percentile = 50th percentile (median)
third percentile = 75th percentile

range

largest value - smallest value

interquartile range

difference between the third quartile and the first quartile

range for the middle 50% of the data

overcomes sensitivity to extreme data values

variance

based on the difference between the value of each observation and the mean

useful in comparing the variability of two or more variables

average of the squared differences between each data value and the mean

standard deviation

the positive square root of the variance

coefficient of variation

indicates how large the standard deviation is in relation to the mean