Data Analysis Flashcards
Relative frequency
Frequency / Total
Areas of a bar graph or areas under a distribution spread
1
Standard deviation formula
(Average(Mean-Value)^2)^1/2
- Calculate means of values
- Find difference between mean and each value
- Square each difference
- Find average of squared differences
- Non-negative square root of the average of the squared differences
Most values are within how many standard deviations of the mean?
3
Intersection of sets S and T
S (upside down U) T
Union of sets S and T
S U T
If sets S and T are disjoint/mutually exclusive, then what does their intersection equal?
0
If sets S and T are disjoint/mutually exclusive, then what can their probabilities not equal?
0
Inclusion-exclusion principle
|A union B| = |A|+|B|-|A intersection B|
|B union C| = |B|+|C| because |B intersection C| = 0
Multiplication principle
First choice possibilities x second choice possibilities
Permutation
Order matters
nPk = n! / (n-k)!
n >/= k
N-Factorial
Common type of permutation
n! = n(n-1)! = n(n-1)(n-2)! = n(n-1)(n-2)(n-3)!…
Combination
Order does not matter
Combination = Permutation / Number of ways to order
nCk = n! / k! (n-k)!
nCk = nCn-k
nC0 = 1
nCn = 1
Probability of an event
of outcomes in the event / # total possible outcomes
If P(E) = 1, then
E is certain to occur
