desc stats - numerical measure reading Flashcards
1
Q
percentile
A
info on spread of data over interval from smallest to largest value
Lp = P/100 (n+1)
2
Q
variance
A
uses all data to measure
-based on diff between the value of each observation and the mean (deviation from the mean)
3
Q
population variance
A
SD^2 = sum(Xi-N)^2/N
4
Q
sample variance
A
S^2 = sum (Xi-Xbar)^2/n-1
5
Q
standard deviation
A
-positive square root of variance
-S denotes sample
-omega denotes population
6
Q
distribution shape
A
-if symmetrical, skewness = 0
-skew left= negative skew
-skew right = positive skew
-symmetric = mean and median are the same
7
Q
skew tells us
A
where extreme values are
8
Q
right skew mean is
A
bigger than median
9
Q
left skew mean is
A
smaller than median
