STAT Symbols and Formulae Flashcards
Memorize common statistics symbols and formulae for GMU class STAT-250
μ
(mu)
μ is population mean
μ (mu) should only be used with
symmetric data
N
population size
n
sample size
p
population proportion
p̂
(p-hat)
sample proportion
median is not used for
population
m
median
m is appropriate for
median is appropriate for symmetric data
x̄
(x-bar)
sample mean
x̄ (x-bar) can only be used with
symmetric data
p̂1 - p̂2
(p-hat sub1 minus p-hat sub 2)
sample difference of proportions
p1-p2
(p sub1 minus p sub2)
population difference of proportions
σ
(lower case sigma)
population standard deviation
s
sample standard deviation
The 95% rule states that if _________, then ________
If distribution is symmetric and bell-shaped, then ~95% should fall between x̄ - 2s to x̄ + 2s
z-score tells____
how many standard deviations a given value is from the mean
population z-score formula
z = x - μ / σ
sample z-score formula
z = x - x̄ / s
z-score is most often between
-3 to 3
IQR meaning and formula
Interquartile range is Q3-Q1
Fence rule
Upper fence is Q3 + 1.5(IQR)
Lower fence is Q1 - 1.5(IQR)
SE
Standard error
The standard error compares
Standard error compares typical distance that a sample is from the center - rather than an individual observation as in std deviation.