Unit 2 Stats

median

The median is the middle value in a data set when the values are arranged in ascending or descending order. If there is an even number of observations, the median is the average of the two middle values. Median is best for data that includes outliers,

mode

Data entry that has the highest frequency. Best central tendency for qualitative data. The tallest bar on a histogram

mean

Avg. value = sum of all data entries ÷ number of entries. Best used for quantitative data with no outliers

symmetric distribution

When the median of a data set is equal to the mode, and the data looks symmetrical on a histogram

uniform distribution

when every data point is the same and there is no mode

skewed left

Long “tail” on the left. Mean < median. Bars further from the x-axis are longer

skewed right

Long “tail” on the right. Mean > median. Bars closer to the x-axis are longer

range

max value - minus value

deviation

each data point value - mean. sum of deviations is always zero

negative deviation

the deviation is less than zero

positive deviation

the deviation is greater than zero

average deviation

sum of deviation ÷ amount of data points. always equals zero

deviation squared

square each deviation, divide sum of deviation by amount of data points,

interval estimate

mean - deviation squared # = lower limit

mean + deviation squared # = upper limit

variance

average deviation

standard deviation

square root of avg. deviation or avg. deviation

population mean

the greek letter µ (mu) is used to represent the:

sample variance

population variance

sample mean

x̄