Mean, Median, and Mode3.1 Measures of Central TendencyAverage:
one number to represent an entire population Modethe value that
occurs most frequently in a data setorder the data set when it
contains a large number of data valuesNot very stable (changing one
number can change the mode dramatically)
Mediancentral value of an ordered distributionequal number of
data values above and below ituses position rather than specific
valueif extreme values of the set change, the median usually does
not
To find the median:Order the data from smallest to largestOdd
number of data values middle numberEven number of data values sum
of middle two values 2**If you have a large set of n data values,
use (n+1)/2 to find the middle value.Mean = sum of all data values
number of data valuesResistant measureone that is not influenced by
extremely high or low values.Mean is NOT resistantMedian is more
resistant, but a disadvantage is that it is not sensitive to
specific size of data value
Trimmed meanmean of the data values after trimming a specified
percentage of smallest & largest data values (usually around
5%)More resistant than the mean, but sensitive to specific data
values.To find the trimmed mean:Order the dataDelete the bottom and
top 5% (round to nearest integer)Compute the mean of the remaining
90%HOMEWORK:Read Sec. 3.1 and do problems on p.81-82 #2, 6, 7, and
8
