Variables
x̅ Sample mean x + alt 773
µ Population mean Alt 230
n Observations sample
N Population
σ2 Population variance Alt 229
σ2 Population standard deviation
s2 Sample variance
s2 Sample standard deviation
X2 Chi-squared
A∪B The union of two events Alt 8746
A∩B The intersection of two events Alt 8745
α The significance level Alt 224
, Mode
The value that occurs with the greatest frequency
Mean
Σ xi
x=
N
Median
The 50th percentile
- n = even average of the middle two samples
- n = uneven the exact middle
Population variance
Population standard deviation = σ = √ σ 2
( Σ ( x i−µ ) 2 )
σ 2=
N
Sample variance
Sample standard deviation = s = √ s 2
2 ( Σ ( x i – x )2 )
s=
n−1
Coeffecient of variation
( StandardMean
Deviation
∗100 ) %
Chi-square
2
2 ( Oi−E i )
x =Σ
Ei
Oi = Observed Value
Ei = Expected value
x̅ Sample mean x + alt 773
µ Population mean Alt 230
n Observations sample
N Population
σ2 Population variance Alt 229
σ2 Population standard deviation
s2 Sample variance
s2 Sample standard deviation
X2 Chi-squared
A∪B The union of two events Alt 8746
A∩B The intersection of two events Alt 8745
α The significance level Alt 224
, Mode
The value that occurs with the greatest frequency
Mean
Σ xi
x=
N
Median
The 50th percentile
- n = even average of the middle two samples
- n = uneven the exact middle
Population variance
Population standard deviation = σ = √ σ 2
( Σ ( x i−µ ) 2 )
σ 2=
N
Sample variance
Sample standard deviation = s = √ s 2
2 ( Σ ( x i – x )2 )
s=
n−1
Coeffecient of variation
( StandardMean
Deviation
∗100 ) %
Chi-square
2
2 ( Oi−E i )
x =Σ
Ei
Oi = Observed Value
Ei = Expected value
