center 5#summary
DESCRIPTION
TRANSCRIPT
Numerically
Mean: arithmetic average, add all observations together and divide by the number of observations.
If there are n observations which are labeled as ;The mean is
Read as “x bar” Must be written with the bar!!!!
1 2, ,..., nx x x
1
n
ii
x x
25n27 4 14 9
25x
9.92x
the middle obsevation Arrange the data in order from least to
greatest If an odd number of obs. find the middle
number If an even number of obs. find the average
of the middle two numbers
Order:2 2 3 4 5 5 6 6 7 7 7 7 7 8 9 9 9 10 11 12 14 16 19 27 35
Med =
If the distribution is symmetric the mean the median will be approximately the same
If the distribution is skewed to the left, the mean will be less than the median
If the distribution is skewed to the right, the mean will be higher than the median
The mean is affected by outliers and the median is resistant to outliers
When the data is symmetric use the mean When the data is skewed use the median
Numeric description of the distribution Minimum 1st Quartile (Q1) – Middle number of the
bottom half of the data Median 3rd Quartile (Q3) – Middle number of the top
half of the data Maximum
Put data in order2 2 3 4 5 5 6 6 7 7 7 7 7 8 9 9 9 10 11 12 14 16 19 27 35
Min = 2 Q1 = 5.5 Med = 7 Q3 = 11.5 Max = 35
Graphical display of 5 number summary
Range = Max – Min
Interquartile Range IQR = Q3 – Q1
Any observation below the Lower Fence (LF) or above the Upper Fence (UF) is considered an outlier
LF = Q1 – 1.5(IQR) UF = Q3 + 1.5(IQR)
If outliers are present the whisker extends to the last value not an outlier
The outlier is marked with an x, box, or point